Personally I'm willing to give him another season. I won't shed a tear if he goes, but I could stand another season to see who he brings in and if lessons have been learnt from this season.
That's not backed by stats or analysis, just gut feeling that season three is make or break (so tear that to shreds if you want since its just opinion).
If a new manager came in, I'd expect a season free of relegation worries (mid table all season), and top 10 would be a good achievement.
If it's Lambert again, I'd want to see top ten no matter what.