I think this implements the changes recommended by the Monero Research Lab in MRL-0004
Does this also deal with the second hard fork in MRL-0004 to require a minimum mixin of 4 after 2 years?
It doesn't right now. The plan is to feature freeze the forks six months in advance (I think there is a thread on this at the getmonero forum). There are certainly other important features that will need to be forked in like multisig and others, so there will be more forks (unless development stops of course, but let's face it, if that happens the coin is in pretty big trouble).