Don't Fret Gents. KTM has told the offroad community that they plan to continue making 100/ 200/ 250 / 300 motors, indefinitely. If they continue to make the motors, parts will be available. Oh yeah, KTM's new 250/300 XC-W come with . . . push button start. Now that would be a great line of motors for any Bike or Quad.
Stryder, I hope that the YZ holds out but Yamaha seems to be leanin' in the direction of Honda, Kawasaki, and Suzuki. All have dumped their 2-stroke line-ups. Sadly Suzuki sold more RM250 in the last year due to their popularity in GNCC, WORCS, and Endurocross. But teh popularity was overshadowed by the influence of SX/MX on buyers. (well Ricky and Ivan ride RMZ's . . . I want a RMZ.)
Hopefully FMX will help keep the YZ250 around. You just can't Jump anything else like a YZ.