Massive Spanner
The Football Wrench
If Evra can't last till 32 then I don't see Baines doing it, so I'd say that's 3 years maximum you can expect the same level of him, by that logic. Evra is much more athletic than Baines, so you'd think Evra would have more longevity in that regard.
But I don't think Evra showed lots of signs he can't handle so many games. He lead our team in starts and appeared in more games than any other player, which I believe he's done a few times for us. I agree he's made some strange mistakes, but it does seem that SAF is asking him to spend most of his time in the other team's half, I can't believe he's just forgotten what defending is.
I'm not saying Evra can't last til he's 32, in fact I'm sure he can last longer than that, but at 31 he shouldn't be playing pretty much every game for us, especially seeing as that man runs (or used to run) more than anyone else on the pitch, and he's so reliant on his pace. I think he can still give us 2 or 3 more years, but only if we have someone else here too to ease the burden on him, and decrease his game time by 15 - 20 games a season perhaps.
Lately a lot of his defensive problems have been because he's been slow to get back after bombing forward, looking a bit knackered. I don't remember that from the Evra of old.