As you say, there are a couple of scenarios where the Sheikh could walk away and sell up. However, him "getting bored" is the unlikeliest of the lot and I find it completely and utterly astonishing that, just 13 days shy of the 7th anniversary of the ADUG takeover, there are still opposition fans out there that peddle such a desperate line. GDM has made the point on numerous occasions that there can be few things more intoxicating than owning a football club. Of all the Sheikh's business interests, City will give him more enjoyment than most, if not all. We might not be making him anywhere near as much money (thus far anyway) than some of his other ventures. For example, one clear case in point is that him dabbling in those Barclays shares a few years back made him billions, but I can guarantee that watching City will be far more entertaining for him than watching Barclays share price increase.
Also, I concur that if the Sheikh exited now then it's unlikely that the club would implode due to the fact that it's grown exponentially over the past 7 years and much of the infrastructure is now in place for long-term sustainability. With next to no debt to speak of, we'd be an attractive proposition to a lot of potential buyers.
While there are indeed a lot of intelligent posters on Red Cafe, anyone spouting this kind of hackneyed bollocks is as thick as fucking pig shit.