[clyde asbury]

There's a good set of articles in January's issue of Sky & Telescope called "NASA's Other Space Telescopes."

It details the Chandra, GALEX, Spitzer, and Swift space telescopes - all still in operation. They don't require servicing as Hubble does.

[RadioAstronomer]

They don't require servicing as Hubble does.

And Hubble has no onboard fuel to prevent deposits on the mirror. Hubble was modular and not only designed to be serviced but upgraded as well. It is a platform like no other. Loss of Hubble will be a great loss indeed.

The Webb cannot replace Hubble.