Will we see the return of low level vulnerabilities?
With the efforts towards the migration to IPv6 (and all the protocols related to it, such as ICMPv6) and DNSSEC, a lot of vendors are running to add the support for those protocols to their products. Vulnerabilities in protocols at the lower ISO stack levels haven't been common, but there were plenty of those when the Internet became popular (remember the Ping of Death?). The times when you could bring down a system with a simple "ping" seemed to be over, but now, with a lot of new code handling the basic stuff being deployed, we'll probably see again a surge in vulnerabilities like those being exploited.
However, the scenario is quite different now. Some factors that may make things different:
The Internet now is slightly different from that one in the 90's...I wonder what could happen if someone finds a new PoD Today.
Developers know that their code will be attacked, that things like "buffer overflows" can be exploited. Big vendors have SDLCs in place.
The research community is bigger and better prepared. A lot of very good people trying to find bugs.
The tools to find bugs have also evolved. A lot of researches are pointing their new shinny fuzzers to everything that runs code.
More powerful and well funded organizations searching for "cyberweapons".
During the last years we've seen the attackers targets going up the ISO layers. With all the new code being deployed there's no reason to believe they won't revisit the lower levels to find "lower hanging fruits" (pardon the pun).