My feeling is that this is close to what they are attempting. From a couple of snippets I've read I think one set 4e rules (likely optional) they will try and keep is some of the battlefield control rules. One of the goals of 4e was to try and make the battlefield a more active part of combat, so rules for pushing, pulling, active terrain etc. I think will make the cut.I think the absolute core will be retrocloned OD&D/AD&D akin to Microlite.
The next layer will be very much 3.5: powerful Vancian magic, feats for fighters, different class mechanics, spells will have specific conditions and details rather than a handy list of universal conditions and timers, 3.5 multi-classing, no roles, more skills. (I also predict no healing surges.) With some Pathfinder-like improvement of casters like first level at-will spells and cleric channeling.
I think things from the Fourth Edition like rituals, martial powers, treasure parcels and milestones will only be represented in sidebars and slim optional books. I also strongly suspect that in order to build a 4th style fighter you will have to sacrifice a lot of damage and feats to get a few cool but nerfed powers. But as long as the Wizards keep the Fourth Edition Character Builder operating, I will remain happy.
Given that dragonborn, eladrin and warlords loom large as "the implied setting of 4E" for me, and mechanics come secondary to getting the world behind the game right, then yes, I can't see 5E as anything other than Fourth Edition 2: Electric Boogaloo (now with added Castles & Crusades*).
*: If the source on dragonsfoot is any guide.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.