He led West Ham to two top 7 finishes, was in Europe and won a trophy. To me the expectation for any manager is top 10 next season, push for Europe the following season. If we start slow next season we should move on (I don't follow the logic that he's only here for the last 5 months of the season).
We have an incredibly unique opportunity (or problem depending on your perspective) in that we have so many first team spots available this summer. This summer will be transformative simply because of the circumstance we find ourselves in. He shouldn't be given free reign this summer, he should have someone guiding him with a vision, and if he doesn't follow through next season I doubt he will be here very long.