Kagawa could play deeper, will he offer as much there, not in my opinion and unless we're going to get Rooney to play in the hole this season then I think we're gonna see similar problems to the ones we've seen in the past, where we struggle to get in to some games and that's because we'll let ourselves get outnumbered in the middle. Kagawa in his normal position would counter that and allow the likes of clev, ando and even Carrick a way to get more involved in the attack. If he's not doing that role then I hope Rooney is.
Specifically on Kagawa deeper, I think it's a bit more complex then saying scholes did it. Scholes as a striker/number 10 wasn't the same as kagawa, in the same way Gerrard as a number ten doesn't play it in the same way Silva/Iniesta/Ozil etc would. Same position, different execution. Personally I think Scholes's style lent itself more to being a box to box player when he went into midfield and then to the deeper player he is now. He didn't drift in and around games in the way the likes of kagawa, silva etc do.
Also as I've said before it was different when Scholes played. Teams played 442 which meant his lack of defensive talents weren't really exposed as he just had to pick up his man and we didn't get so overrun in the middle and he could get forward much easier as he really had only one man to beat. These days the majority of teams play 451/433, we're usually outnumbered 2 to 3 in the middle and with most teams playing so narrow in reality it's more then that. I don't think you can really have a midfielder who played like scholes did, in a two man midfield at the moment. Not as successfully and particularly without someone dropping in to that deeper role, between the midfield and attack to facilitate someone pushing ahead. If they try it without someone dropping to cover then imo we're very open to the counter.
If we do put someone there then Kagawa could be effective there, if not at his best. I guess in the end sometimes you have to sacrifice one player playing at their best for the good of the team. However I think that if we play rooney and rvp quite high and neither is told to actually stay in the hole that whilst in some games we will be amazing, in others, the likes we've struggled in before we'll see the same problems. The midfielders won't be able to have a large attacking influence because they'll be isolated and we'll still suffer from defensive frailties from his lack off training there.
We'll have to see I guess. Fergie has been talking about Kagawa as one of the striking options which has given me some hope, but I can't see the logistics of how he'll play there regularly. Like I said I'm sure he can play a deeper role, however I think we may well be missing out on a great way to make the team more dynamic by doing so. On the other hand if Rooney goes back to his original role and can add more consistency to his performance in deep areas then it could well make us an even better team, though if kagawa is there on a regular basis then it'll be a shame for the likes of clev and ando.
To keep my post on topic somewhat, regarding Hernandez, well I'm not sure what will happen with him. Said before that I don't think he has the versatility that Welbeck has which will cost him games, could be a great impact sub, but then would he really make the bench much? Suppose it depends on what happens with the wingers but I'd expect the normal bench to include the likes of welbeck, young, ando, with giggs, scholes, hernandez, fighting for the other attacking spot. Be interesting to see.