Eep!
NO! NO, NO, NO! Definitely wouldn't like that! Sounds so "cliche". Roxanne should either just disappear from the plotline or just make brief "cameos". I want the next films to focus more on JB's coming to terms with his powers without any of that "lovey-dovey" stuff getting in his way. We need a much darker plot for the next films. I doubt putting Roxanne back will do any help.
I'd rather have it if JB simply leaves Roxy
for good; Instead opting to fully embrace his curse & 'mastering' its use. The trilogy (if we're gonna have one) should be left open-ended with GR still running-around avenging innocents and stuff.
I've always enjoyed open-ended films. It's like when we finish reading the latest comic book issue & are left to wonder: "Where will the road take GR next?", or "What new journeys await him?" IMHO, its much better compared to finishing the plot altogether with JB renouncing his powers just to get a "fairy-tale" ending with Roxanne (that would stink!

).
Also, leaving the trilogy still open for future plotlines is actually a good thing!

That way, it's more possible to create "spin-offs" like a live-action (or animated) series starting where the movies left off. (Hmm, yeah! A "Ghost Rider TV series" would be cool, indeed.

)