That's right, Dybala's future at Roma is even more secure than at Chelsea and as you said he has always had a starting place under Mourinho's command. Actually, Dybala is still relatively new to joining Roma after being brought in since last season from Juventus, so he still feels he has a responsibility to complete his duties with the Roma wolves. Chelsea are not likely to push Dybala too hard and besides they are now filled with many young players and I think choosing Dybala who is almost 30 years old is certainly not the right choice.
If Dybala is still very suitable and comfortable at AS Roma, I don't think he needs to move to another team for next season either. Especially if the choice is Chelsea, which slumped last season, so obviously it will be very difficult for Dybala to return to develop there with the young players who have been brought to Chelsea. So it would be great if Dybala wanted to continue his career with AS Roma next season by continuing to work together so he could bring AS Roma to a better position than last season.