The transition is definitely something to be nervous about, but it could work. They had no problems transitioning from GB/GBC to GBA afterall, and I could see this being similar situation. GBA ended up selling a lot less than GB/GBC but that was because Nintendo felt the need to rush out the DS due to Sony releasing the PSP. There probably won't be any major shakeups as far as new competitors are concerned this time around.
Had the PSP not existed, the GBA likely would've had more time in the limelight and would've been much closer in sales to GB/GBC. Possibly still not outselling them but maybe it could've been over 100 million. Over 100 million for a successor to a system that sold over 118 million is very impressive.







