Kiko Macheda struck twice in victory over New England Revolution this week.
"We've not made that decision yet. Both (Mame Biram) Diouf and Macheda were out on loan last season and (Danny) Welbeck," said Ferguson.
"They deserve to come back to the club and show in the pre-season and their work in training, how far they've progressed. It may not be that either of them or any of them go out on loan – they may all stay.
"That would give me a problem in terms of giving them enough game time, but it's the kind of problem we've dealt with many times over the years. It wouldn't bother me if they all stayed."