[Wmshyrga]

50 years is highly unlikely. just developing the mining techniques to be used let alone the actually equipment will take longer than that. then there is the human facto to be considered, "how safe will this venture be?", as if it is going to be a commercial operation then killing their staff is not a good pr exercise.

Took 9 years to get to the Moon once they decided to give it a go.
50 years for asteroid/Moon mining would be highly likely once they decide to make an effort...and that may well be the case before we all know it.