Um, how about McTiernan returning to direct one final Die Hard film?
Screw this brain dead idea of an origin/sequel, and just make a final sequel, with McTiernan back to finish it on a high note.
I don't care about how McClane started, and does anyone else with half a brain care? I doubt it.
Get Bruce back, help him give a good performance like he can when he really wants to, get John McTiernan back to direct and maybe Shane Black to polish the script. Get a better villain than from those last two fake Die Hards, and make the movie a legit R rating like the first three.
Easy.
Maybe have Bruce look like this http://www.imdb.com/media/rm888660480/nm0000246?ref_=nmmd_rg_md2
If the studio had balls, they'd do something like this, to ensure that at the very least, we'd get a pretty damn good movie.
Keep the budget smaller than the last two pretend movies, and make it more like the original in terms of containment and location restrictions for the character.
Don't include Jai Courtney or Mary Winstead, and don't mention them. Pretend as if they don't exist, and that John's kids are played by different actors. Get Holly back for at least a cameo, and if need be, set it at Christmas again, though that's not a deal breaker to me, considering the first two were set at Christmas.
Basically, if you do all or most of this, you'd have a good product, one where Bruce would probably try to do a good acting job.