Presently only about handful of rakes are available both with CR and WR. Although MRVC has placed a bulk order for AC EMU rakes, they are expected to arrive only from second half of 2023. Otherwise the rate of arrival of an AC EMU rake to Mumbai has been like one in about 4-6 months.
Railways planned to operate only AC EMUs on Mumbai suburban, eventually at Metro rates (something like DMRC). Think about the present rolling stock of non-A/c EMUs. They are good for at least 20 years more. They may...
more... utilize DC-AC converted non-A/c rakes to increase services on TNA-KYN section, since they are good for at least another 15 years. Also, presently not in use AC rakes of BHEL/Alstom may be put in service.
There is no point in bringing AC fares down to Metro fares just now. But as an indicator towards that, they can at least halve the fares till there is a suitable time to implement Metro fares. Mind well, AC rakes have hard seats (like Metro) -- without cushions like in FC.