People would keep playing and then carry on with a new edition when it finally came out, or keep using what they had.
Just like they did at the end of 2E, when TSR went under and we had almost a year with no new product at all.
Heck, for many of us D&D was effectively out-of-print during a few years of the 1990s. D&D was dead to me for most of the 1990s.