I think the difference between what we get now and what we might lose out on by waiting a season or two, is what we're really gambling on. We're not gambling on £50m, we're gambling on £10m or £20m, if we keep him and he helped us get in the CL, or a trophy, or even the league, then it's a gamble that will have been worth taking and the difference in transfer fee in the broader picture becomes irrelevant.
He's not going to drag us towards a title challenge or Champions League place, though. For one, he's not at that level even when his attitude is at its best and he sure as hell won't now. His relationship with the club is over. We need to rid our hands of him and reinvest the money into Lacazette. It's the best piece of work we would do all summer.