The "easy" answer is Sid. I know he hasn't been able to actually challenge McDavid but I think he still has enough left in the tank to take one more Art. Kuch is also a good option.
The season before last he had like .03 ppg worse and led the league in goals while missing 7 games. Finally getting the rest he hasn't had in years and him being 31 now he might recognize this as his last real shot at challenging McDavid in the scoring race and go all out in the regular season. I suspect McDavid still wins it but I wouldn't be shocked if Crosby managed to be a close 2nd.
While it's not an accurate depiction of his play, Crosby still hasn't put up 90 points in years and is going to be 31. I think he can still be the best player in the world in spurts but I don't know if he can keep it up long enough to win another Art Ross at this point. Went with Kucherov, as he was the leader for much of the year and is smack dab in his prime.
Something I've learned since 2005, never bet against Crosby or count him out. That's why I'll vote him until he wins the poll.
With McDavid off the board, this poll assumes who is most likely to win among the above. IMO, Crosby probably won't together a consistent enough season of dominance to beat McDavid at this point, but I think he's shown over the last 5 years he can beat everyone else on this list still.
I think last season is clouding people's opinions of Crosby's ability to finish high in scoring. Like I said, prior to last year, he's finished 1st, 2nd or 3rd in scoring 5 straight seasons. That's better than anyone on that list.