Yes, I think that the housing market will eventually crash. Markets are cyclical. Every time that prices reach high levels, the bubble eventually bursts, and prices go back down to a reasonable level. It's very important for homebuyers to not purchase any more house than they can really afford on their income.
With the glut of expensive homes on the market a new housing crash is most certainly on the horizon. Coupled with the government's willingness to repeat past mistakes of forcing lenders to give mortgages to people who have no business getting them, this is all setting up for yet another collapse. Why we haven't learned our lesson the first time around is beyond me.
No, the number of expensive homes on the market does not necessarily signal a coming housing crash. It simply means there are many people wanting to sell their expensive homes. There could be several explanations, but the one that makes the most sense is that people are recognizing the problems associated with large expensive homes--things like upkeep, expense, time and effort expended--and that the expensive house does not make them happy. They are simply downsizing their home to increase their family happiness.
A new housing crash is not on the horizon, despite a reported glut of expensive homes hitting the market. The build-up to the last housing bubble was led by easy credit, which is no longer the case. Banks lent freely, but now there are safeguards. Additionally, lenders are more wary, having gone through the recent cycle.