The lights are already out when you are looking through a barrel.
DBs will not be obsolete. ever(that means at least 10 years) :-)
It depends what you are talking about...
Hi-res sensors >24 Mpx
large > 24 * 36mm sensors
detachable sensors (DBs)
Because of minor inconveniences like the wavelength of light, you cannot get much benefit out of much more than 24 Mpx from a 24 * 36mm sensor, so Canikon will have to invent bigger cameras to join the game.
High-res cameras do not have to have detachable backs, particularly if each back is calibrated to a single body as with Hasselblad - I have a DB cos I have a MFDVC (Digital Medium Format View Camera).