Bitcoin doesn't need to increase its throughput. This is what layer 2 (3,4,...,n) solutions are for. This is like saying "Well, the dollar is useless because Fedwire TPS doesn't accommodate all transactions." If you compare apples to apples, Bitcoin is more than adequate to replace something like Fedwire with a zero trust decentralized system. Layer 2 solutions for Bitcoin can look something like The Lightning Network (trustless) or something like the Liquid side-chain (maybe for institution-to-institution settlement?).