I've long defended LT's slow demise and yes, it's probably because of those championship winning years.
What I saw of him during the game didn't look quite as good as the OP is making out, although that catch/TD that was called back looked much closer to vintage LT than he has in the past two years.
I do think there are a handful of people who are seriously undervaluing the difference the Jets O-line will make vs. the Chargers O-line. Those are the same people who think Thomas Jones is going to light it up in KC too (and probably will defend his 2 carries for 2 yards in *his* preseason game).
I'm not saying LT is going to (or should) get 100+ carries this season, but I do think he'll be a viable option for the Jets at the goal line and a great 3rd down guy. He'd also be an instrumental part of an RBBC with McKnight if Shonn Greene were to get injured.