If you're asking about mixing franchaises (like Archie cast with Fleetway cast, Sonic Boom, Sonic X, Underground etc.) then answear for now is 'no'. As far I know Sega own all of them, but doesn't wants to confuse people or something like that. The best thing we have is Archie Sonic, combination of games, Aosth, Satam and it's own thing. Sonic X and Underground were other dimensions (before the reboot) but I think there are off limit for now. Howvere there is upcoming crossover with Sonic Boom.
But if you're asking just about that whole thing with Penders and reebot, then it's 'no' for now and I'm 90% procent sure it will for ever be 'no'. Even if Penders agreed to give his characters back, Archie would still have to hunt after other writers like Bollers or Strom. And even then it would be pain in the ass to somehow put them back in the comics (for example Nicole has new origin now).
So our only hope is that Archie will somehow find those documents that prove that they own all pre-reboot characters and then decide to bring them back. Unfortunetly chances are really slim.