I think we'll sell anyone that can be sold. I don't think anyone, including Grealish, is safe. Some players won't accept the pay cut that comes with relegation, others will think they're too good for that league.
They may not have a choice. Their wages are in their contracts, so "not accepting it" isn't really an option unless somebody wants to buy them. Then it comes down to how much the club are offered.
If somebody were to offer us £6/7/8m for the likes of Ayew or Gana then we'd probably take the money. If somebody offers us £1/2/3m for then, then I expect we'd choose to hold onto them.
See the likes of Hull - I reckon that had somebody better come in for likes of Hernandez, Diame, Huddlestone, Dawson, and they'd offered Hull enough to make them want to sell then they'd probably have left. But they didn't, so they're still there.
Also, for the ones that we'd have an interest in keeping, their reduced salaries probably are still likely to be more than they were earning prior to joining us - the likes of Gana and Amavi were earning between £15-20k per week in France.