I have the same exact question. SONOS team, could you please let us know if and how we’ll be able to continue using our Time Capsules as our Music Libraries for SONOS?

As long as the TIme Capsule supports SMB v2 or v3. 

Apple TC is SMBv1 and is not changeable.

Then no.  The S2 app for Sonos now only supports SMB 2 & 3.  The uproar from a few very vocal doom and gloomers caused Sonos to remove SMB 1 support due to security errors that were never seen to affect Sonos setups.  Blame the vocal minority for that one. 

S1 still supports SMB 1, and I have seen talk here of rollback to S1 being made possible by Sonos again after some unspecified time. 

Whether you can live with S1, and whether all your kit can work in S1 is something to also be seen though.

Unfortunately most newer Sonos speakers are not S1 supported.