This is quite possibly a question we'll never be able to answer with any certainty. There's no doubting his talent ability to bowl well, but due to his injuries, just how good his career could/would have been will never really be known I fear. All good test bowlers are capable of perfoming exceptionally, but the difference between just being a good bowler and being in the top echelon of bowlers in your time is consistency. Jones proved against best team in the world that he has what it takes as a bowler, but it must be taken into context. It was still only one series - one series in a career that has been fairly poor excluding it. It was also at home in helpful conditions for his bowling, and it was also as part of a performing, effective attack to back him up with the team on a role.
He has the ability to bowl brilliantly, no doubt. But so do lots of bowlers. Doubts over his consistency, his ability away from home and how he'd fare in a weaker attack or in poor conditions for his bowling will never be removed unless he can string together a year or two or consistent performances without falling injured - something I'm not sure he can do. Even if he does come back from his latest injury, there's no certainty that he will ever fully reach the standard he set himself - and there's no real way of knowing what his career would have been like without his injuries.
That's the grand scheme of his career though in comparison to other bowlers. In terms of his selection, there's no doubt in my mind he should be in the England side if he's completely fit and shows any signs of form early in the county season.