I think both have a chance, but Hingis probably has MORE chances, because she will probably play longer now than Lindsay will. I think if Davenport does not win a slam this year, she will seriously consider hanging up her rackets. I think ironically, Lindsay's best chance should have come last year, with the Williams sisters not being on form MOST of the time, and with the Belgian sisters injured much of the time and the top Russians struggling, and no Hingis to boot.
Right now, the Belgians are pretty much back and up to speed, Mauresmo is obviously playing her best tennis ever and the Russians, at least some of them, are looking good again, all spells trouble for Lindsay. And now there is Hingis, too, who is probably only going to get better as the year rolls on. And Hingis is both hungry and now even much more of a fan favorite. My guess is, Martina will get a minimum of one more slam singles title before she hangs it up and maybe more than that.
I am not optimistic about Lindsay's chances any longer.