On the ground I agree Jones uses his reach well, both for takedowns and GnP, if were talking standup though I think its a mistake to believe every MMA fighter with a long reach is going to exploit it aswell as your typical boxer does. I agree its really hard to see Jones not being able to take Shogun down reasonabley often if he brings anything like the aggresion he has to his recent fights. The difference is though what actuaslly happens on the ground, wrestlers like Bader, Vlad and Hamil are obviously not going to be comfortable off of there backs but Shogun has a far stronger BJJ background and a history of being hard to hold down. His reach/body type could work agenst him on the ground aswell with those long arms easier to catch from the bottom plus of course Rua has a history of controling tall guys like Overeem well when he gets ontop.
I don't think JJ will stand with Rua at all. Just enough to get Rua in a position to go for the takedown. As for Rua controlling taller guys on the ground I would stick my neck out and say that I cannot see any man at 205 putting JJ on his back and controlling him.
I doubt Shogun will take him down that often(although its always possible in a high tempo aggresive fight) but being swept is I'd say a real danger and thats arguebley the strongest area of Rua's BJJ plus he often doesnt need long ontop to end it.
if he embarasses rua then machida, couture, rampage, evans and co have nothing for him. he doesn't need to face a wrestler and i think rua is a better striker than any of them. they would provide different styles but i think he would be like silva and look for an intriguing challenge rather than want to just keep defending. jones must know that heavyweight lay in his future.
I'd say Jones is actually more likely to make a quick switch to HW if he loses badly to Shogun rather than if he dominates him. Giving up the title and main event status so quickly wouldnt make sense for him or the UFC, if he were to get beaten down by Shogun though HW obviously offers a new challange and an easy way to rehype him.
Forrest is big too and he obviously didn't need to move up to HW after beating Rua. Has Jones ever missed weight? Would Jones v Machida not be an interesting matchup assuming Machida and Jones win? Sure, Rua might be the "better" striker but Machida presents something completely different. What about Rampage? If Page is motivated he is going to be hard as hell to take down and has a lot better boxing than Bader. There are absolutely matchups for Jones at 205. If Jones wants to be an all time great fighter he needs to get a belt and defend it.