Their official statement was, that now the GPT versions will only improve in small steps, and no really big releases at a time. This would mean, that they only saved the trademark for later use, so that no one else gets it. But, while this was an official statement, OpenAI is still a company, so they might have made this statement just to appease their competitors.

My guess based on those statements is, that GPT-5 releases around mid of next year, but we'll see.