When the late Ken Campbell applied to succeed Trevor Nunn as artistic director of the National Theatre, his proposals included plays by Neil Simon, Eugene O'Neill (The Hairy Ape starring Bob Hoskins), Steven Berkoff, John Arden, a new version of Mary Poppins, Jim Carrey as Hamlet and Measure for Measure "translated into English."

He also outlined projects that might have involved Terry Pratchett, Brian Eno and Ken Dodd. He received a letter from the NT chairman saying that Nunn's successor was about to be announced (this was Nicholas Hytner, who took the reins in 2003) and that they'd decided not to call him back for a second interview.

I'd love to have seen Hytner - who has confirmed that he steps down (along with his executive director, Nick Starr) in two years' time - hand over one of his auditoria to Campbell for a "guest season" but, strangely enough, he's prosecuted many of Campbell's ideas anyway in his advocacy of children's shows, free-for-all circuses (in the summer seasons outside) and Sunday openings, though he drew the line, alas, at Campbell's proposal of a musical version of Jack London's Call of the Wild with a chorus of singing dogs.   

There's no disputing the fact that Hytner has made the most tremendous job of running the National, not just in producing two money-spinning blockbusters that simply could not have been produced by today's West End operating independently, War Horse and One Man, Two Guvnors, but in promoting great work from directors as different as Marianne Elliott, Katie Mitchell, Howard Davies and Danny Boyle; classic performances from Simon Russell Beale, Alex Jennings, Fiona Shaw and Adrian Lester; the plays of Mike Leigh and Alan Bennett; the collaborations with Punchdrunk and BAC; the ground-breaking musical London Road, rare Ibsen and just now The Curious Incident of the Dog in the Night-Time.

And, of course, he'll be most remembered, perhaps, for having introduced the cheap sponsored ticket scheme (though critics say those Travelex bargains were always snapped up by NT regulars anyway) - and rewarding the benefactor, Lloyd Dorfman, by re-naming the Cottesloe in his honour, a false move in my view - and the NT Live series of broadcasts around the UK and the world.

What should his successor be thinking of doing? Seizing back the initiative from the fringe in the Edwardian and immediately post-war British repertoire; establishing an ensemble within the company, perhaps like the Bill Bryden company under Peter Hall, to explore poetic drama past and present in the Dorfman; commissioning a five-year plan of new work from Alecky Blythe and Adam Cork; new plays from James Graham and the Lucys, Prebble and Kirkwood; doing more Irish and Scottish drama, and with more conviction; ensuring that we have the next, and the best, work of those great survivors, David Hare and Howard Brenton.

With Michael Grandage and Jamie Lloyd dropping anchor in the West End - and rumours of the two Nicks joining them there, too - and with Rupert Goold committed to the Almeida, and Gregory Doran sure to shake up the RSC repertoire with telling and long overdue raids on the Jacobean canon and Ben Jonson - carving out a special identity for the National in the next decade will become increasingly difficult. One objective might be to harness the vitality and innovation currently going on with site-specific and landscape theatre, though Vicky Featherstone might have something to say about that at the Royal Court.

Featherstone will announce her summer plans next week, and it will be fascinating to see whether these will leave John Tiffany and Jeremy Herrin, say, free to concentrate on a bid to take over Hytner's job. Either would be a very good candidate, and so would Dominic Cooke, but my information is that Cooke is "knackered" and wants to go freelance, like everyone else.

The NT board simply must find someone young and enthusiastic enough to re-create the theatre in their own image and likeness, and this is a tall order when the organisation is so huge and unwieldy and so demanding in its thirst for "product." Which is why Jonathan Church at the Chichester Festival might well emerge as a front-runner.

Myself, I'd like to see Marianne Elliott have a change of heart over not wanting to run the place, and who could rule out the remote possibility that either Sam Mendes, or Stephen Daldry, or even Danny Boyle, might fancy five years at the helm, with meaningful associateships with firm prospects attached handed out to Jamie Lloyd, Blanche McIntyre and - someone who might even be capable of taking on the top job herself - Lucy Bailey?

Three or four years ago, it looked almost certain that Michael Grandage was being positioned as Hytner's successor, in much the same way as Terry Hands identified Adrian Noble as his successor at the RSC and, way before that, as Peter Hall had anointed Trevor Nunn at the RSC and, when he had crossed the floor of the house, Richard Eyre at the NT.

But that certainty has now evaporated, and the future looks anything but obvious. It's not impossible, of course, that the board may already be thinking "Tom Morris", who's a brilliant operator and very clever. And surely Jonathan Kent, who ran the Almeida so brilliantly with Ian McDiarmid, should be considered? 

There's long been a feeling that one of our great companies should once again be run by an actor, and I couldn't think of a better trilogy than Simon Russell Beale, Harriet Walter and Daniel Evans to job-share the position with a red hot executive director - Alan Finch at Chichester? Stuart Rogers at the Birmingham Rep? Nick Allott from Cameron Mackintosh? Padraic Cusack from within the NT itself? - setting the course with funders, creatives, the media and the audiences. There's an enormous task and duty ahead.