Probably they will add the old pendulum zones when pendulums came, to make a "progressive story" of the game, since we already have synchro but still no the extra monster zone.
I wouldn’t mind for it to be put in yugioh duel links because it is a neat summoning feature, also only thing I would suggest is to maybe limit the amount of cards for pendulum to like 10 pendulum cards
Reply if you agree
Since there's only 3 monster zones, it makes them pretty balanced already. along with that, they could just not add the REALLY broken cards (Searchers for searchers and all that)