Yeh, Vic's done little wrong all season, I just think we look less balanced with the Wanyama/Dembele combo as I think Vic likes to get about; lacking the discipline of Dier (think it'll help Dembele's game too).
Other options that I'd consider (depending on the game):
Wanyama / Winks
Wanyama (as sole DM)
Dier / Wanyama (for tough "can't lose games")
I also really liked Wanyama/Alli in central midfield when they partnered eachother.