If hosts' own antibodies only last a few months, bad news: odds are high that vaccines will likely only be relevant for a few months as well (including spike protein oriented MABs). Hopefully, after surviving a few bouts, it becomes nothing above a severe cold and no longer life-threatening. One potential snag is a few documented reinfections have actually been worse, hyperimmune reactions. Impossible to say if that's due to host factors or viral load/exposure.
Leronlimab is going to play a critical role as a last lifeline in the event of a hyperimmune response... Which may result almost immediately from vaccines and prior infections in some people.
This is totally neglecting to mention the shortage of other MAB's... Not everyone will be able to get those; they'll go first and foremost to health care providers, guaranteed.