1. Require all providers install and manage firewalls on all subscriber connections enforcing source address validation.
i can see how the end to end principle applies in cases 2 and 3, but not 1.
I didn't make any of these up. They've all been proposed by serious, well-meaning people.
i recommend caution with your choice of words. apparently not everyone treats "well meaning" as the compliement that it is.
If you have 2 and 3, why do you need to waste global addresses on 1.
i don't believe that 2 or 3 will ever happen, for simple market reasons -- it is harder to make money if you do 2 or 3. however, 1 only costs a small bit of ops expense, and has no market impact at all, so it's practical in simple economic terms.
Its a mis-understanding of what source address validation is. Some folks think it should work like ANI, where the telephone company writes the "correct" number on the call at the switch.
ouch. i guess you're right. perhaps a copy of BCP38 should come with every router sold?