The BBC DG has announced a long list of expected closures.The official text of his remarks makes no mention of a specific date for closing LW. Here's what it says:
"We do plan to stop scheduling separate content for Radio 4 Long Wave, consulting with partners, including the Maritime and Coastguard Agency, ahead of the closure of the Long Wave platform itself. 5Live on Medium Wave will also close no later than December 2027, in line with a proposed industry-wide exit from the platform."
https://www.bbc.co.uk/mediacentre/speeches/2022/digital-first-bbc-director-general-tim-davie