It is a completely different Lego market than when the original UCS MF was released. Lego is falling over gobs and gobs of revenue from a diverse set of sources.
They're leading the toy industry with essentially a single product.
I think the higher likelihood is that a UCS MF would be available for an extended period of time - much like the Sandcrawler, Simpsons D2C, Tower Bridge or the Death Star. There may be periodic shortages like the Saturn V, but eventually new stock would arrive. Given the much higher number of premium sets available that appear to sell well, rolling out one super-premium set seems comparatively less risky than it was over a decade ago.
Someone seeking a +$500.00 UCS MF set isn't likely to buy something else with their Lego dollar. They'd just wait for stock to return, which would create cyclical demand for the set.