As soon as we get some. Main metrics of usefulness would be survival rate in hard vacuum, cosmic radiation and absolutely minimal or extreme temperatures - divided by volume, weight, price and energy requirements - and further by the useful work it can do per unit of time.
In conclusion, not any time soon. Humans will return to the Moon only when we accept that our presence there is purely symbolic/for the cool factor, and decide to eat the enormous price tag.
In conclusion, not any time soon. Humans will return to the Moon only when we accept that our presence there is purely symbolic/for the cool factor, and decide to eat the enormous price tag.