Can we rely on the sell a player model forever without investment?. Personally I don't think so. If anything we have been extremely lucky to have a few players coming through the academy that we can sell off, unfortunately we are seeing recently a few signing for bigger clubs before we can cash in on them.
I don't think the Well society can sustain the club at its current level and probably not if we were in a league lower with the lack of premier league gates and revenue.
I honestly don't know what the answer is however I don't think we can continue the way we are we can't go into every season with our fingers x that we don't get relegated and a player plays well enough to sell on.
Finances are yo-yoing no matter how you try to spin them.