There's been some discussion about Windows Mobile 6.5 and non-touchscreen phones, namely that everything we've seen has been on touchscreen devices. And as of right now, the only phones we know are getting an upgrade to 6.5 are Professional devices like the HTC Touch Pro 2 and Diamond 2. That's not to say that Standard phones won't launch with 6.5 already on board or get upgraded – we just don't officially know of any yet.
But fret not. Windows Mobile 6.5 will at least run on on Standard devices, according to the Marketplace Application Standard Guidelines (pdf):
It is highly recommended that applications should have the ability to run on two or more Windows Mobile 6.5 device platforms, for example, multiple Standard and/or Professional devices. Writing to multiple Windows Mobile devices helps extend the market opportunity for developers and gives end-users greater choice when making purchase decisions concerning both applications and Windows Mobile devices. This requirement is waived for ruggedized devices, which also referred to as Vertical market devices.
That should kill off any fears. The question remains: Which Standard phones will it run on?