[from the REN-news mailing list]
As of the 1st of January, all the Region Internet Registries (RIR's),I suppose this is a bit like the USG jump-starting DNSSEC by requiring it be present for the .gov TLD. But only a little bit, because in this case the pressure on the vendors is going to be coming from annoyed customers.
that being, AfriNIC, APNIC, LACNIC, RIPE and ARIN have adopted a policy which allocates 32bit ASN's by default
[A]lmost no networking equipment out there
currently supports these.
This means that should you get a 32bit ASN instead of a 16bit ASN, it
will not be useable to peer with or announce to the TENET network or
most other networks at this point.
And since there's no backwards-compatibility built-in (no fall-back number), Metcalfe's Law works against one here: everyone you need to peer with also needs updated equipment and/or software.