As Warwick's relationship with Edward collapsed in 1469 and say he holds off the marriage of Clarence and Isabel Neville that year (the King was against the match anyway). Which means Clarence is still available when Warwick cuts his deal brokered by Louis with Margaret of Anjou. Then you might get a double wedding in 1470 - Isabel Neville to Edward of Westminster and Catherine of Lancaster to George of Clarence.
Under those circumstances George is going to be a much bigger threat in the 1470s and given his own high handedness might find himself short by a head sooner rather than later - much will depend on whether he consumates the marriage and produces an heir (Catherine will be 12 ish at her marriage so if George can last as long as in otl it is likely they might have a child).
Under that it is far more likely that Edward will posthumously attaint Warwick and grab the whole estate for the crown - if Richard still marries Anne Neville the couple may be granted some of her father's northern lands (an attainder would protect the lands Warwick held in right of his wife who was still living and those would still be able to pass to Anne and Isabel on her death).
Assuming Edward IV dies on schedule then Richard will find it much harder to usurp the throne because deposing Edward V is going to give the rag tag of surviving Lancastrians a real obvious candidate (who is in England) and who has a claim in both the York and Lancastrian lines. It might be safer for Richard to allow his nephew to rule.
The problem I see with your scenario is that George turned against his brother because Edward IV said no to allowing George to marry Isabel. He sided with Warwick and married Isabel in secret in Calais. If Warwick doesn't marry Isabel to George then George has no reason to betray his brother.Warwick would also be less inclined to arrange a marriage that doesn't directly benefit him. George has no reason to be loyal to him so why would he help secure a good marriage for him?