Yes, they could have a very significant foothold in the battle for civil rights, if they did not get viewed as a bunch of radicals who only know how to solve problems through violence and riots, which is not the answer to solver any of the problems african americans face.
Yes, the Black Panthers could gain a significant foothold in the discussion for civil rights if they were to sever ties with criminals such as the murdered George Jackson, because aligning with people who used physical force and intimidation is not the way to engage in a discussion. The Black Panthers need to drop the violence completely, because that is the opposite of a discussion.
Although there is always room to improve an organization's image over the years, such as the IRA did in Europe, there will always be inklings and memories of aggression and marginalization. Severing ties with criminals will indeed help their cause, but at least in the era of the next 30 years or so, the Black Panthers will not be able to gain a foothold in a serious debate on civil rights.
The Black Panthers are outdated and have been since the 1970s. They are a small voice among African-Americans in the United States today. The Black Panthers won't gain a foothold in the discussion for civil rights no matter what they do in the eyes of the public. Too much violence has been associated with the Black Panthers in the past to rectify any future with the organization.
I do not believe the Black Panthers could gain a significant foothold in the discussion for civil rights if they were to sever ties with criminals such as the murdered George Jackson. Many fronts of the civil rights movement have been justified in America since they were brought up about five decades ago. Pushing for more rights would be asking for rights above and beyond others.