One thing to be said for Contagion is that it's unlikely to bring Kate Winslet another award. Alternatively, there might be an award for anyone who can come up with a good reason why she made Contagion, a picture that takes a vast subject and reduces it to amazing banality. Yes, it is by the same Steven Soderbergh who made Sex, Lies and Videotape, and if you recall the journal he wrote about the making of that film, and the brave new world of independent projects he foresaw, this is a sad comedown.

But that's not Winslet's fault. Perhaps she did this confident no prizes would be offered. For I take her to be a reasonable, good-humoured actor who knows in her heart how silly it is at 35 to have been nominated for an Oscar six times. This record surpasses Bette Davis, or anyone else, and as Winslet heads towards her 40s who can doubt she is our next Meryl Streep? Not that you can tell from the awards. She got an Emmy for her Mildred Pierce, an addled performance opting for class and slowness when James M Cain's trashy novel required the full-charged melodrama that Joan Crawford gave it in 1945. But some people seemed to think with Winslet in the lead this adaptation could be dragged out over five episodes – or was it five months? It was dreadful, and the Emmy went on reputation alone, but it's good to see Winslet falling on her lovely, intelligent, earnest face sometimes.

Not that we don't think the world of her. She was so good and desperate in Revolutionary Road I nearly forgot to wonder why her character had ever dreamed of marrying Leonardo DiCaprio. She was so memorable in The Reader (the film for which he actually took home an Oscar – she has won only once) I was ready to forgive the mishaps of bad luck and pregnancy that had kept Nicole Kidman out of the part. After all, Winslet did German English as if born to it – she is nearly as good at accents as Streep – but Kidman's Germanic touch might have been something to treasure.

It seems as if Winslet has been there all our respectable lives – doing Thomas Hardy (Jude), Jane Austen (Marianne Dashwood in Sense and Sensibility), not to mention the young Iris Murdoch in Iris (though I'm bound to think that if Ms Murdoch had been quite that glorious and as much given to skinny-dipping she might never have been driven to writing novels). She was outstanding in Philip Kaufman's Quills, she went for the daring of Eternal Sunshine of the Spotless Mind, and she was naked and smiling at DiCaprio in Titanic, the film that changed her life, I suppose, but not mine.

With all those to her credit, it seems refreshing that there are dull spots – The Life of David Gale, Finding Neverland and All the King's Men, in which I can barely recall her trying to work up heat in the southern gloom. But don't forget her in Peter Jackson's Heavenly Creatures, a film that depended on her quality of peril, and just marvel at what there must be to come.

Except that her career already suggests the opposite. It is so hard to count on a supply of new parts. As soon as you get The Reader, you have to expect a truckload of Contagions being dumped in your lap. That's when you begin to realise the uncanny accomplishment of Streep, getting into her 50s and still commanding roles such as Julia Child and Margaret Thatcher. Where does Winslet go – Elizabeth David and Hillary Clinton? Hamlet? Queen Lear? Alas, those dreams of classy operations perished with the decline of Kenneth Branagh (Winslet was his Ophelia, if you recall). After Mildred Pierce, she may have to settle for doing so many old chestnuts, from Anna Karenina to playing Crawford herself. And I'm afraid I can see them in advance. So here's another question: if Kate Winslet had six Oscar nominations by the age of 35, how many will she get by the time she's 55 – and name three parts that will get the nod?