The government's transport decarbonisation document is now out. There are no commitments to MML or any other specific electrification schemes, but it does say "
We will deliver an ambitious, sustainable, and cost effective programme of electrification guided by Network Rail’s TDNS."
(The TDNS, published last year, recommends electrification for most of the network, with a limited role for battery and/or hydrogen trains.)
See this thread, e.g. post #21:
Department of Transport has made a written statement on this but supporting documents and specifically the Rail Environment Policy Statement not yet posted on the DofT website. Thi document will look at The government is also publishing its rail environment policy statement, which will set...
www.railforums.co.uk
It remains to be seen how much longer we will have to wait for specifics.