Though Mumbai still has suburban rail systems, metro lines paralleling with them seem to be built.
It will be needed to mitigate crowded trains on those suburban lines.
On the other hand, Pune, the city which is 130km away from Mumbai, seems to build Pune Metro Line 3.
I wish there would be an intercity metro line between Mumbai and Pune, though it's difficult to say Pune is the suburban city of Mumbai.
I guess these 2 cities will be connected by expansion of suburban areas of both cities. Then, each metropolitan areas will overlap.
If that happens, the intercity metro line won't be a delusive rail.