This is the stupidest decision Lotus could make if they dump Grosjean mid-season.
Why? How could any other driver do worse job than Grosjean is doing? With Grosjean they will most likely end up 4th in the championship and Kimi’s championship points alone will ensure they can’t drop to 5th place. So there isn’t really any risk in dumping Grosjean.
Grosjean has already had about two full seasons in Formula One and there has been little progress (in fact, I think he has regressed this season), so it’s not like keeping him would be a good investment either. I believe the only think that has been protecting Grosjean for so long is the fact that his manager is Boullier, but that can’t save him forever.
I think that if Grosjean is replaced, it will be someone outside the team. Valsecchi would probably struggle, even if getting him experience now could pay off next season. Kovalainen, Glock and Kobayashi seem good choices, even though I don’t have any information on whether Lotus has contacted any of them or if they’d be free to join Lotus.