This is not the right strategy, at least it's not right to get rid of iDVD.
My boss is going to switch to Macs later this year. The tipping point? My taking his vacation videos and making a simple but cool-looking DVD from them (in one night). That's 3 Macs that will be bought because of iDVD.
I can't believe people want their wedding, vacation, performance, etc. videos only online, instead of on DVD (of course, I still buy CDs, so what do I know?).