I'm not sure what are you trying to suggest. I hope you are not trying to say Royce gracie can beat Bruce? lol. Royce has no standup at all, he will get knocked out (he won't get Bruce to the ground.) Bruce had displayed knowledge of grabbling and submission as well (this includes rear naked choke, guillotine choke, side choke, takedowns, etc.) The point is Bruce is well rounded, he knows enough grabbling and submission and has the strength and speed to submit his opponent or get out of a submission attempt by his opponent. Chuck is a one dimensional fighter and not a good one either. He won tournaments by scoring more points than his karate opponents, based strictly in karate rules and in a karate environment. So if Chuck is to step out of his comfortable environment then he is no longer protected from those rules; therefore, he will get knocked out or submitted very shortly. What will happen, will depend on who he is fighting (I wasn't necessary referring to chuck fighting Royce.)
Also, keep in mind, Bruce standup game is amazing, so good luck trying to get him on the ground in the first place. His techniques, speed and power (he has great knockout power) are not easy to overcome. Besides, ground work is useful in the octagon but not necessary in a real fight (even MMA have its rules.) There are so many techniques (like triangle choke and armbar for example which I know will not work in a real street fight.) You just need to know how to get out of them (it's not hard at all) and Bruce know how to get out of a bad situation. And lets not all forget that Bruce was doing this decades ago. So you comparing Chuck with Bruce is stupid.
And by the way, why are ppl putting Bruce in his opponent's environment and comparing the situation anyways (like fighting karate guys in a karate match, a tae kwon do guy in a tae kwon do match or a grappler in a grappling match.) Any logical thinking person will know it's unfair to begin with having Bruce to follow their rules (not that I think he will lose, just making a point.) If you have to imagine putting Bruce in that situation (meaning in a handicapped situation) in order for that person to even stand a chance against Bruce, then that opponent is not worth mentioning.
The fight should be anything goes - as simply as that and it's fair. At the end, Bruce will win, simple as that.