Honestly, I think Liverpool can compete just fine with City, the addition of Van Persie makes a huge difference for United, but you can see on the field that they can keep up with anyone. Chelsea and City both have huge questions, mainly, what is going to happen with thier managers at the end of the season. We all know that Benitez isn't going to be at Chelsea, and who the hell are they going to hire? I mean they have hired big name after big name, and I don't think even Blues fans are so delusional that they think Sir Alex is going to jump ship and the mad Russian is not about to rehire someone he fired. As for City, Mancini knew last year that if he didn't win the Premier league he was gone and this year they are completely falling apart, he's having issues with players, so one is left to wonder what will happen to him at the end of the season. With the type of money being spent, they should be putting a lot more hardware into the trophy cabinet.
Everton, Tottenham, and Arsenal all have their upsides and downsides, but the talent gap isn't as huge as the big money teams, if Chelsea and City had the managing talent that united has with Fergie, I think it would make the BPL a lot more exciting. Also, with Everton and Liverpool it's always a toss up, Everton plays Liverpool really hard, and Liverpool often fails to show up to the Derby.
As I said, I don't realistically seeing it happen this year, I think that opportunity went away over the last two weeks when Liverpool left 4 points behind due to mistakes. But it will be interesting to see how they finish off this season, last year the wheels fell off and they dropped over the last 10 games, hopefully this year we can reverse that trend.