Military planners, tacticians, and commanders are the only ones in a position to answer this question intelligently

They possess the information regarding what tech is needed to future-proof the machines as well the intel necessary to understand what threats need to be defended against. That being said, the military industrial complex often ensures that project costs balloon exorbitantly. The entire process for military hardware acquisitions, storage, and logistics needs to be reviewed and reformed to reduce waste, fraud, and abuse.