I don't think this case will help. The court ruled that there was no rational governmental purpose to denying felons licensure as precious metals dealers. While you or I may not agree, I can see a court saying that ensuring that guns do not fall into the hands of folks who have a known propensity to break felony laws is a rational governmental purpose.
The key is that the rational governmental purpose test is based on that activity not being a fundamental right. As the RKBA is important enough to be enumerated, it can be argued that it is fundamental. Therefore, this ruling would not be precedential to overturn laws that prohibit felons from possessing guns. There is actually a completely different and stronger argument to be made. A rational governmental purpose, even if found to exist, would not justify the ban as it would have (had it existed) in this case.