I think KERS is too big in racing to ignore it anymore. They have a car that is famous for being a hybrid coming up at one stage or another (P4/5 Competizione from 2012) so they just have to do it. DRS should be relatively easy, as they already have active aero implemented so it's just the rules that need to be implemented, and P2P should be pretty easy once KERS is implemented as the idea of a boost would be there, it's, again, just a matter of implementing the rules.
I think as long as the basic frameworks is there, modders may even be able to figure something out for themselves once the modding tools come out and everything is ready for them to begin the work.