Subsidies would be useful in getting it from $108/MWh to $54/MWh faster, but they don't change the underlying physics of the technology.
Sorry, what I mean is that the $48/MWh figure benefits from significant subsidy; it's not a realistic cost of provision.
Perhaps surprisingly, it is a realistic cost and could be much lower if the electricity market were efficient (as opposed to being an amalgam of regional monopolies with essentially no price incentives).