This is what worries me, but for a different reason. I tend to think nature is sometimes smarter than we are, and if our bodies are deciding that it's best not to let antibodies stick around too long after infection, I'm left wondering why?
Of course it could be that for some reason it's difficult for the body to maintain the antibodies, or it could be that evolution has made it advantageous not to do so. The big worry would be that these types of coronaviruses are prime candidates for antibody dependent enhancement as the virus mutates, so our immune system has evolved to not risk hanging onto antibodies that could make future infections much worse. If that were the case, then a poorly designed vaccine that causes sustained presence of antibodies could compromise us over the long term. I believe this is what happened with the aborted dengue fever vaccination attempts.
As pro-vaccine as I am, I am concerned about the short time-frame over which the trials are being conducted, especially when the virus is still in the early stages of mutating. All that said, the scientists developing vaccines are much smarter than I am, and I'm sure are well alive to these concerns and the potential risks.
If a vaccine is approved, I will take my chances and get the jab.