Doubling down on what I said in the Unsworth thread. This is a horrible idea.
Main Reason: He has no workable role. I'm sure we'd like to play him as a pure DM but he doesn't have the positional discipline, so the next option is to use him as more of a box-to-box player. The problem? He can't pass the ball in/into the final third effectively and he regularly kills attacks (or worse, starts counter attacks for the opposition). Could he be used alongside a positionally disciplined passer? Maybe, but unlike Kante, Gana has never shown any ability to use his defensive work to help us counter. So really, I'm not sure what his value to the team is. Tackles and interceptions aren't worth anything in and of themselves.
Secondary Reason: He relies on his pace to make loads of tackles and interceptions. Once he's past age 30, that pace is likely to decline, which means he won't be able to do nearly as much of what he's built his reputation on. His current contract expires after his age 30 season and, to me, that's perfect. His value will only erode from there.
He has a role in the squad but he's nowhere near worthy of being top earner and/or someone we build our team around. There, I said it. Tool away.