If I were INXS, I would want someone to go in a new direction. After all, they weren't exactly hot when Hutchence was still fronting them.
As far as Marty: I don't think the "grunge" scene really exists anymore, either. He is actually the closest thing to a new direction left.
In general, it is extremely difficult to return to fame. I have seen many bands sounding not-half-bad on "Hit Me Baby One More Time," "Bands Reunited," and "Re-Making." None of these people or groups (including the lovely and talented Taylor Dayne) have been able to make any sort of splash again.
I know this sounds rude, but I just don't think any of the remaining singers can bring INXS back (in the USA, internationally a different story). And maybe no one would be able to. It is very difficult.
Van Halen is the only band I can think of that was able to do what INXS is attempting, and that only worked on their first try (Hagar). Their second try (Cerone) didn't go so well.
As others have mentioned, if any band might have a chance at making a comeback with a new singer, it would probably be the abovementioned VH.
The Stones have never really gone away, plus they are huge legends. Their existing fan base keeps them going. Like the Eagles, most of their fans are still their original fans. I doubt either group has gained many new fans in the past 20 years.