Gas turbines impose an impractical air-intake burden on submarines

Could gas turbines make a K-class-style fleet submarine practical?

Probably not, because the required air intakes would be difficult and hazardous to route through a submarine hull.

A gas turbine needs an immense volume of air. Routing and sealing that much intake trunking through a pressure hull creates serious design risks, making the apparent speed benefit much less attractive for a fleet-submarine concept.