I have been receiving thin white paper stock boarding passes from UA 1K ticket counter instead of thermo paper.
1. It looks just like a regular paper stock boarding pass with the vertical perforated line on the right.
2. It does not have the horizontal perforated line in the middle of the stub.
3. It does not have the magnetic strip in the back
4. It has the bar codes

Maybe this is replacing the thermo paper boarding pass.