The BL2000 is Master Link only, it doesnt have a powerlink plus it is not in production anymore.
For the BL3500 you had the same situation, however I know they made a change so that you could use the B&O wireless system and if I recall correct they added an aux but I doubt that you can use that either.
Why would you not want to use normal Labs? BL3 and BL8000 among other have a "Line In" switch and there are adapter cables available.
The speakers you picked are specifically link speakers, you could connect them to an Audio Master and and connect to that the Sonos Player.
Cheers
JK
BS9000, BS2300, BC2, BL2500, BL3, Bl2, BS1, BV8, BC4, A8