Originally posted by Pål Jensen You mix up sensor size with mirrorless or DSLR; two different issues. Sensors smaller will dominate the marked forever, regardless of camera type, because both cameras and lenses will be cheaper and because image quality is better than good enough and on the increase. Mirrorless do not steal customers from DSLR's but from P&S; Canon have just reported 30% increase in DSLR sales and Nikon is making all the DSLR's they can manage. The fact that Canon have not made a mirrorless yet is proof good enough that their market share is not eroding. If it had they would have been quick to fix it. [they probably will make a mirrorless in due course but that is not because of lost sales of DSLR's]
The DSLR marked is just as price sensitive as the mirrorless marked and hence it will continue to be APS dominated. Even a doubling of FF marketshare yields only 10% share; ie a niche.
I differ in opinion... Many people move to dSLR (talking the entry level market) because of a real improvement that is perceived from naive reasons. If you would have read my post, you would have seen that I am talking 5+ years out. I'm not saying that the dSLR market is dying now or that it will die instantly; it won't. Mirrorless cameras aren't there, yet, specifically with respect to a viewfinder. But with Pentax's entries that can utilize the same lenses, it is only a matter of time before the quality of the cameras combined with the ability to use SLR quality glass will take those customers who are jumping directly from P&S to dSLR's to jump to mirrorless instead.
Mirrorless technology is going to cause the lost sales of dSLR's they aren't developing because of loss sales to dSLR's. Companies like Canon, Nikon, Pentax, etc know that a dSLR quality camera without the dSLR moving parts is a win-win for them. As for FF, the reason the FF market is only 5% or even 10% is because of the price, but that price will potentially come down, and if mirrorless really do replace entry-level dSLR's, I can foresee the dSLR market shifting towards FF type sensors in the mid-range. Nikon is already moving this direction with the D600. In other words, the market might split with those that are sticking with SLR's potentially moving into the FF realm. If mirrorless technology can rival dSLR technology at the entry or even mid-level, I don't see where there would be much of a future to APS sized sensors in SLR's except the optical viewfinder.
There are other economics, however, and all I talk about could lead to no increase in FF availability (even if FF sensor costs come down) and the market could just remain at the 5% niche as it is, and the companies could purposely direct the market as they see fit, but I still think the ultimate goal of the industry is to eliminate the mirror-box. That has to be a bit of a liability with respect to warranties.