That is an unsettled question. According to the license itself, you cannot sublicense GPLv2 code. When you distribute a copy of third party GPLv2 code to someone, their license is coming from the copyright owner directly, not via sublicensing through you.
If the copyright holder is no longer issuing licenses, it is not at all clear what would happen. The analysis gets complicated and speculative at this point. There are quite a few plausible theories, but it is going to take a few actual cases followed by appeals for any clarity to start developing in this area.
If the copyright holder is no longer issuing licenses, it is not at all clear what would happen. The analysis gets complicated and speculative at this point. There are quite a few plausible theories, but it is going to take a few actual cases followed by appeals for any clarity to start developing in this area.