DK would have to be willing to block well/consistently if he were used in close to OT. I don't know about him specifically, but WRs are not known to do this both because of skillset and willingness. He would need to put in a lot of time learning some blocking techniques and blocking in-game or the play would be projected just from him lining up inside.
In addition, it would only take one well-placed hand swipe from his blocking assignment to break a finger or wrist ... and he's useless as a WR for the rest of the season.
I'm not saying it's impossible, or even a bad idea. I'm just saying there are some reasons to the contrary even though he (physically) would match up well. If this were in his future, it might take an off-season to learn blocking assignments, technique and additional route tree.
It seems like there's a concerted effort to use NFant a lot more in the passing game. If Fant turns into a catch threat, lining him up at WR it might achieve similar mismatches. That would be a fairly imposing wide out formation- 500lbs out wide v 350lbs of CB. Maybe those infuriating passes along the LOS would actually get yards.