In TTL, Warrick could possibly outlive Edward IV. Warrick was only forty two years old when he died in OTL, so in this scenario I could see him living until the 1490’s. Edward IV would probably still live an unhealthy lifestyle in TTL and die around 1483.
If he marries Bona in 1464, she may have a son (TTL Edward V) as early as 1465 and that son would be eighteen in 1483, thus avoiding a need for a regency. If a regency were required in TTL, then Edward IV would probably make a will setting up a regency council with Warrick, Clarence, and Gloucester among its members. In TTL, I doubt Edward IV would allow his brothers to marry Warrick’s daughters, so it is difficult to predict what Warrick’s relationship would be with either Clarence or Gloucester. Without the Neville inheritance to fight over in TTL, Clarence and Gloucester could pool their resources in opposition to Warrick at court. I suspect that in TTL, Edward V (as heirs are prone to do) would have an opposite idea of how to rule England than his father’s (and by extension Warrick’s). Edward V would probably end the alliance with France and take part in continental wars. He would likely receive support in his warlike policies from his uncles Clarence and Gloucester. Of course, Henry VI and his son Edward may both still be alive in the 1480’s in TTL and Warrick might be in correspondence with the Lancasters.