I believe they are already over the top.
As crazy as it sounds, I'm beginning to lean this way also.
I am not there yet but I am wondering about this also.
The more I look at the NBA this year the more I believe the league has reverted to where it was in 2015 more than 2021 in terms of offensive vs defensive importance due to rule changes on defense.
Sorta early days Warriors when the Bogut - Draymond axis was key to their title run. Defense still not as key as say 2010 or 2000 or 1990 or earlier but more important than it has been for the last few years. With both Boston and Cleveland showing levels of success I would not expect in 2021 or 2020.
Historically, any team that has Boston's level of defense + a solid offense, and even two big time scorers in Boston's case, is a Championship level ball club. I would doubt this in 2021 or 2020 because I believe floor spacing / three point shooting / team offense took on such a larger role ... but I do wonder whether we are back now in 2015 NBA where offense is important but not all becoming.