repairs in 25 years? completely practical. i think, the parts are still out there and can be easily made if the original supply of parts ever dries up, which seems unlikely considering the huge number of cameras out there and the interchangeability of many parts from the m2 with newer cameras like the m6.
i tried the x100 at a camera shop but didn't like the handling much.
i think that the price of the camera is too high for now - that camera's price is going to crash like a sack of bricks over the next 2 or 3 years, yet the x100 does the same things i can do with my m3 or any other camera (except super high ISO)
if i need a compact camera i just use my ricoh GRD III with a viewfinder on top. for everything else i take my M3 or my Bessa-R or any other of my many cameras and snap away.
if you need super high-iso but you want a rangefinder styled camera get the x100 or a leica m9/m10. if you don't need super high iso then don't bother with the change.