This is purely my prediction and it's possible I might be wrong (it's never happened before, but you never know). I think they will push him down our throats, with a series of squash - easy win matches for a couple of months. They might even give him some gold on the way. But I just can't see the fans getting into the character.
The reason I see this failing is very simple. Regardless of the name they give him A-Train, Giant Bernard, Price Albert, The Monogolian, Lord Tensai or even Baldo, he has always suffered from one big problem. Matt Bloom is as boring as they come. He stands like an awkward kid from the 'special' bus, looks blankly at everything, can't cut a promo and moves very stiffly (with the occasional burst of speed). His whole demeanor is so clumpy, uninteresting and slow looking.
Then take his peers. Mark Henry is more intimidating to look at, Kane is more scary in character and Brook Lesner is more powerful in the ring. So where does that leave old Matty boy. Not the biggest, not the scariest, not the strongest, with a bland demeanor and a Japanese based rep that won't wash with the average WWE fan in the arenas.
Maybe his return has been in the planning for a while and they didn't know Lesner was coming back. But talk about over shadowed on your 'scary and impressive' debut!
Within 18 months I see him demoted back down to lower mid card (where he was when he left the E as A-Train) or maybe even FE. Oh sorry I mean he will 'decide' to return to Japan. Not FE.