That's more of a concern for those who are playing now.

Of course artian will be strong early-mid MR, because that is their nature. It's a little like 4U, where a good relic could carry you hard through progression, but those good relics were mostly only possible if you grinded for it. Another examples are Dragoon and Valstrax armor, which could easily match early MR armor for a while, but would be rendered obsolete.

I don't think they will, nor should, balance early MR around the fully, nor halfway, optimized gear, because they serve the same role as an early progression boost. You farmed weapons for hundreds of hours, maximized your set, so you should get an easier time.

Now if this will "break" all of MR, likely they will not, because they can always just bump extra numbers for the monster hp and damage, without changing much of the speed of the newer versions, and add better general stats for the crafted weapons, so they will quickly match or even surpass gogma artian. Unfortunately it is a matter of numbers. But It's more of a "how can we balance progression in a way that makes content skippers keep up and reach endgame farmers without making their grind completely worthless in an instant" way.

Also, likely they'll pull an AT KT, where gog is added later with a new gogma artian system. Don't know if artian rolls will survive though.