Of course, but I would see it bringing a different attitude to Sundays. I'm talking about commercial chains rather than smaller ones though.
I don't think it'll make any difference to be honest.
The only ones I've come across with short Sunday hours are the spit and sawdust one man band type places which won't change as they close so they're not living there 7 days a week, there's plenty of 24 hour gym and the big commercial ones are still usually open till late evening.