The 33-year-old's omission after 118 Test appearances could lead to a full season with the Bears next summer.
"Belly's going to be a huge addition. I've spoken to him and he's incredibly positive," Bears director of cricket Dougie Brown told BBC Sport.
"It looks like he's going to play a significant part for us next season."
Brown continued: "He's going to be training with us and Jonathan Trott, who was also away in Dubai doing some commentary work.
"Trotty's chomping at the bit to get back into it. By his own standards, he was a bit below where he wanted to be. There's no doubt that, when he's at his best, he's one of the best batsmen in the country."
The majority of Warwickshire's players reported back for pre-season training last week.
The exceptions were all-rounder Chris Woakes, leg spinner Josh Poysden, who is away playing grade cricket in Australia, and their two experienced Test players, Trott and Bell.
But, although pleased that Warwickshire will see more next summer of Bell, who had already retired from one-day international cricket, Brown says it is too soon to start debating whether or not he will play another Test match.
Bell is understood to be privately disappointed at the England selectors' decision, especially for a Test series in South Africa, where he averaged over 44.71 in making 313 runs in four matches - including a match-winning century in the second Test at Durban - on England's last visit in 2009-10.
"I'm not wrapped up in making statements about Ian Bell as it's not fair. It's still quite raw for everybody," Brown added.
Warwickshire will welcome England batsman Ian Bell back into their pre-season plans after he was dropped from the squad to tour South Africa.