So Meseta is not carried over. I immediately stopped doing dailies and UQs after seeing that knowing there's no point. I already have several hundred mils, several stacks of Excubes and loads of Lambda Grinders so I'm good for all six episodes if I continue playing og PSO2.
Weapons and Units (armor) get carried over but cannot be used or/and have their effects temporarily reduced until characters reach certain levels again... Ok? So this telling me that transferring of 15 star weapons would be kinda pointless because they don't want ppl to get too OP too soon. Once 15 star weapons' potentials from og PSO2 are fully unlocked (which could mean a long long time from NGS's launch), there could also be equally strong new weapons that are reasonably obtaintable for the new players because otherwise it wouldn't be fair for them, and it would defeat the purpose of restricting Meseta transfer which is intended for fairness.
Therefore, if someone wanna keep playing on og PSO2 knowing that their stuff, when transferred over in just around one year of time, wouldn't make too big of a deal, then they can go ahead.
Of course, they can make changes to transfer restrictions at any time which could invalidate everything I said above.