No sporting organisation is truly sustainable, simply because they are a relatively small number of bad decisions away from sporting failure which is usually accompanied by falling revenues and attendances.
Manchester United are making money because they climbed to the top of the tree and were there when TV contracts brought an explosion of money in to Football. The financial momentum of football over the last quarter century has meant that by being good at the right time and keeping stable structures for the duration, Manchester United have ridden the wave very effectively.
But compare Manchester United, one of the sport world's financial success stories, to a trusted and profitable company in an established non-sport industry. That business is likely to be an order of magnitude more stable than Manchester United.
Sport is an unpredictable zero sum game. At the end of the season there has to be a team at the top of the league and one at the bottom. It's never about how good your team is or how good your staff are, it's simply about how good your team is in comparison to your competitors.
Should the financial bubble ever burst in Football - and economics suggest that it must at some point - then the clubs with the largest financial commitments are likely to be the ones that struggle the most to adjust.
We do not need to be run sustainably in the traditional sense, but we should be run prudently. We do need to be in a position where we aren't in immediate jeopardy if we have unexpected shortfalls, lose investors, fail on the field, etc. There should always be a plan B and C that can see us work our way out of the problems.
But having any plan B puts us in front of most sports clubs.