Re fears that development of Mac-native apps will diminish: no way. It will INCREASE because of Boot Camp.
Demand for native Mac apps will increase faster than ever now, and demand drives sales. Developers won't turn away now!
The only way demand for native Mac apps would decrease is if the number of Mac users willing to "settle for Windows" increases FASTER than the overall growth of the Mac OS X user base.
Settling for Windows means rebooting, giving up iLife and all your Mac apps, abandoning the security and ease of use of OS X, and--don't forget--PAYING for a copy of Windows. That's too much to settle for unless you have to. And then you'll do it only WHEN you have to. Not by choice. You will still demand OS X and OS X apps.
So I see the number of Mac users willing to settle for Windows being VERY small, increased only slightly by people now choosing Boot Camp Macs for their next "PC." (A great many of them will end up using Mac OS X even if that wasn't their intent at first.)
Meanwhile I see the overall Mac user base growing a LOT--and growing even more because Boot Camp gives switchers a reassuring safety net.
Result: more Mac OS X users, more Mac OS X apps. Not less.
Also,
the smart buying plan for Windows Vista fans is now clear for 2006: You can't buy a Vista PC this year, so don't waste your money on XP, buy a PC that doesn't have Windows at all--a Mac--and enjoy it until Vista arrives

You get the best of all worlds... and you may find you don't care so much about Vista after all...