There’s no logical reason for them to loan him out. It just doesn’t make sense. They’re financially so superior that there’s no chance to make a good deal. It’s not like he’s even riding the bench.
The only way to get Pogba is paying more than United did.
If it's a flat loan yes, probably not much. His price could rise if we can get better performances from him in Italy and CL. But that is minuscule, I agree.
If they plan to sell him and there aren't many other offers (that he will accept anyway, considering Mino was trying fecking City their archrivals) - this is the best backdoor sale they could make. Loan with a hefty option and a big loan fee. Pogba and Juve have to negotiate a new contract from 2019 onwards (4-5 years) and Juve pays the big loan fee (covering wages and part of his value in 2018/2019) and signs him (still for a hefty fee ~ 50-70m) from 2019.
In reality Manchester might not be even making a loss or even some accounting profit from such a scenario. Surely, they aren't making money (and they were never likely to), but they save face and most of their cash.