I was appreciative of the job Main done as a lone striker in the second half of the season, but as noted above, that was massively helped by the fact that we had a midfielder in Turnbull and a winger in Hastie regularly contributing goals in this period, where Main scored once.
The thing for me is that if Turnbull goes this summer, I don't know how likely that is personally, then I'm guessing it gives us a midfield three of Sloth/Campbell/Polworth. While Polworth's numbers stack up well for assists, he's never been prolific in terms of goals.
I think the closest I've ever seen to a central midfielder getting 15 was Stephen Pearson getting 9 in 2015/16, but this was in a season where both Moult and McDonald hit double figures.
Again, I don't know how likely Turnbull is to leave in the summer (he may even get loaned back if he does go), but if he does, I think it's much less of a long shot trying to replace those goals in a centre forward, rather than a like-for-like midfielder. Considering that, I think it's probably best that Main's no longer on the wage bill.