You'd be forgiven for the impression that the announcement of Gay Byrne's radio retirement was the moment RTE had been waiting for. Hot on the heels of Mr Byrne's Sunday revelation, media reports cited RTE spokespeople talking about changes in the Radio 1 schedule, about "shorter, more focused programmes", about chopping the daily soap, Konvenience Korner, about "new talent".

It was hard to believe we were in the depths of the media's annual summer torpor, and the five months until Gaybo's departure will clear some space for new arrangements.

By Tuesday we saw RTE putting some perspective on the whole business and the Director of Radio, Helen Shaw, eulogising properly: "There'll never be another Gay Byrne . . . It will be with a great deal of sadness and nostalgia . . ." etc.

On the face of it, the elegiac tone was more appropriate than the hints of a brave new radio world, and not only because grave-dancing tends to lack a certain grace. The fact is that Gay Byrne had, in the last two years, already moved to a relatively quiet corner of Radio 1's programming and hardly posed a substantial obstacle to reform of the schedule.

Those RTE sources who have been "spinning" to the contrary for some time, suggesting that Ms Shaw's revolution could only take root once Mr Byrne moved on, now have a chance to turn this frustrated rhetoric into liberated reality.

Ms Shaw's first year in charge has already spawned rumours of "blood in the corridors" in Montrose, but the bleeders have been middle- and low-ranking staff and obscure editorial structures. If the post-Gay schedule is really going to be radically different, powerful egos are going to be up against the wall.

David Hanly, Richard Crowley, Aine Lawlor, Pat Kenny, Des Cahill, Sean O'Rourke and Marian Finucane: they're the on-air personalities still very much in place on weekdays between 7.30 a.m. and 3 p.m.

If Ms Shaw and Radio 1 editor Ann-Marie O'Callaghan plan to do more than swap around time-slots, as Kevin Healy did with Mr Kenny and Mr Byrne, someone is bound to suffer.

What's at stake? A year ago, Ms Shaw told The Irish Times: "This is not a station with problems." She meant that Radio 1 remains, in spite of competition from a plethora of commercial stations, a remarkably powerful and popular broadcaster.

New JNLR figures, due out next week, may put some wrinkles in the image, but won't alter one unmatchable statistic: about three out of every five Irish adults listen to the station every day.

What's more, most of that listening is concentrated in the daytime hours beloved of advertisers. One programme, Liveline, has an audience unheard of in other markets at its time in the afternoon.

The retirement of Gay Byrne reminds us that Radio 1 will never be the culturally dominant monolith it once was, but it's still an imposing edifice. (Just look at what happened to Radio Ireland when it tried to challenge Radio 1 on its own terms.)

But the statistics also hold a warning which Ms Shaw is trying to heed. The Radio 1 listenership is worryingly low among people under 40 years of age; below age 30 the most apt description would be "negligible".

This age structure poses a dual threat: for one, the audience is subject to what's politely called "attrition", listeners literally a dying breed; and older listeners are less attractive to Irish advertisers than their high-spending offspring.

The last couple of years of the Gay Byrne Show seemed to make a virtue of this bias in the listenership. But Mr Byrne's granny-oriented radio (call it GOR) was only an extreme, and often quite charming, version of what many listeners perceive Radio 1's programming to be like right across the schedule: stodgy, unchallenging, overly familiar, middle-of-the-road.

That perception is exacerbated by a widening gap between what the station offers and what is available from other broadcasters. BBC Radio has changed considerably in recent years; in particular Radio 4, the nearest equivalent to Radio 1, has spawned the trendier, laddish 5 Live and also shipped some of its heavier "public-service" baggage (including some more awkward dramas and documentaries) over to Radio 3.

All three stations work very well with their renewed identities, and BBC Radio 1 and Radio 2 also have kept their music programming alive and alert. The soccer explosion alone has ensured sports-heavy 5 Live a substantial audience in Ireland, much of which carries over to its "news-talk", a much-admired format which has yet to be effective in an Irish context.

Dublin listeners have also turned in their droves to something different. Local stations 98FM and FM104 have imported the "zany" breakfast-show format from commercial stations abroad and also introduced frank (i.e. often obscene) late-night phone-ins. The confessions and confrontations of Liveline can sound pallid compared to the hyped-up outpourings on these latter programmes.

In this context Radio 1 sounds more like "a station with problems" after all. So what is to be done? The obvious solution of importing Gerry Ryan could be dodgy for 2FM; and it's as well to remember that it's not so long since Pat Kenny was the bright, with-it young fellow who was going to make RTE sparkle.

Ms Shaw says the station recognises "the intimate and personal relationship between Radio 1 and its audience. The last thing we're going to do is something that's `radical' or `explosive'. We want to strengthen that connection rather than turn the whole thing upside down.

"Gay's departure is not a defining factor, but the show goes on and we have to move forward into a new phase. There's a constant need not to be complacent. When we have to change and move forward, we should do that as sharply as possible."

She recognises the importance of Radio 1's personalities. "What I should be doing is playing to presenters' strengths, and investing in the content of the programmes." Ms Shaw's apparent emphasis on programme formats rather than personalities is probably healthier in the long run.

Her own instincts, in as much as they are visible in the new Five Seven Live, seem to be in the direction of news-talk; Ms O'Callaghan's background in music may also point to a schedule that alternates more clearly between speech and music. Whether this mix can hold an audience remains to be seen.

In the medium term, next year's expansion of FM3 to a full-time station means, presumably, that Radio 1 will be able to lose some of its arts, serious music and drama programming, opening space for more "young" shows.

And some years after that the development of digital radio, with a half-dozen stations where there is one today, will mean the final triumph of some market-led form of pluralism. The idea of a single, all-encompassing, broadly targeted, public-service "flagship" station will probably be a thing of the past.

Harry Browne is Radio Critic of The Irish Times