my gooseberry bushes have also ended up that kind of shape. i have been cutting out the middle to leave the ‘wineglass’ shape, which seems to work despite there being no leg.
i’d be a bit worried that cutting the whole bush back to just one stick in one go would be too much of a shock for the bush? the pruning that you’ve already done should have rejuvenated it quite well.
if you do cut it right back to create the leg it might be an idea to plant the stems that you remove, as cuttings, which you can train from the get-go into the traditional shape. plus then you also have some insurance as at least some of them will live!