well.... do original DS and DS Lite were trash when DSi released?

tbh I will feel nothing. they ain't forcing you to upgrade. besides, the earliest other can get the new models are next year. (it was confirmed for europe that it won't come this year & i'm pretty sure NA region is also the same)
plus, i bought my ds lite in 2008, then i learnt that dsi is coming later that year. I didn't regret it at all

nope. they need something to boost the hardware sales in Japan. Sales are already diminishing/stagnating there.

yeah.. just like in the past when there's dsi exclusive games that ain't playable on previous ds models

No. Yes.

EU