I don't think it's unreasonable to hold out hope for Kawahi.
My best guess is he certainly opts out. He can sign a big one-year deal in Dallas, sit out a year to rehab and walk into a handshake max contract the following season. That maximizes his earnings potential and puts the Mavs on Nets & Lakers level superteam status with two top five players and KP as the third option. Very enticing offer from a front office Kawahi can trust.
My best guess is he certainly opts out. He can sign a big one-year deal in Dallas, sit out a year to rehab and walk into a handshake max contract the following season. That maximizes his earnings potential and puts the Mavs on Nets & Lakers level superteam status with two top five players and KP as the third option. Very enticing offer from a front office Kawahi can trust.