I'll split the difference and say 7.5 carries.
In 12 games, that's 90 carries and 60 catches. I'll go on record now and say he doesn't get 150 touches this season.
Damien Martinez led the team last year with 176 scrimmage touches. Fletcher had 122. (And this is in 13 games). I don't see Lofton getting to 150 this year, not with Fletcher and Lyle (and Pringle?) also in the backfield.
I think somewhere in the neighborhood of 100 touches is probably best case.
Remember, as involved as Arroyo was last year, he only caught 31 passes in the regular season. So if you say Lofton just slides in directly for Arroyo and it's a 1 for 1 swap, he's going from Arroyo's 31 catches to 60? And you're gonna tack 7.5 carries a game on top of that? No way.