The only positive from selling Skipp is whether Ange decides to include Devine and Donley in his squad (both would qualify as List B players so in addition to the rest of the squad) on the basis that he can split the minutes Skipp would have played between them in europe.
IMO both have played well in pre-season and in terms of playing quality done as well (or even better) as most of our midfield options - Devine can play as a DLP ala Carrick as well as an AM, whilst Donley could understudy Maddison as well as being LB in easier EL games - which could usefully strengthen and add depth to the squad.
But they'd need to play say 1,000+ minutes each as otherwise both likely to get more out of loans : Ange could keep them and try playing them until Christmas when we have easier EL games and maybe League cup, before deciding on his playing requirements in 2nd half of the season.
Long term the aim should be to include them as Club trained players to increase the size of the squad in future seasons