Also, with 32bit ASN's, also expect upto 2^32 routes in your routing table when each and every ASN would at least send 1 route and of course there will be ASN's sending multiple routes.
Only if EVERY ASN were allocated and active. You and I both know this doesn't begin to approach reality. Slightly more than half of current ASNs are actually in the routing table. The ASN issuance rate is not likely to go up simply because we go to 32 bit ASNs. Probably we are really talking about a need for 20 bit ASNs or so, generally, but, 32 bits is a much more convenient boundary for lots of code implementations and lots of hardware, so, 32 bits is the chosen number for the sake of simplicity.
32bits ASN would thus just mean the end of BGP...
ULA will do much more damage than 32 bit ASNs. Owen -- If it wasn't crypto-signed, it probably didn't come from me.