Is not guaranteed who Margaret Beaufort would pick Margaret of Clarence for her son. Still the Clarence kids would be excluded by the succession of throne
Henry after his return is an adult man, he can pick his wife on his own. I don't know. Ed V was reported to have some health problems and Edward of Gloucester (Middleham) won't probably survive past his OTL death date. Ed V was an intelligent kid and probably won't risk the end of his dynasty with his brother, so I think after death of TTL's Edward of Gloucester, Edward, earl of Warwick would be reinstated to succesion.