I'm also not sure if there's any "casual" guild will ever return to Season of Mastery. The only thing I'm curious about is how many WOW TBC Gold players like me want this.
It's difficult to convince yourself to play SoM at first, as it's likely to come with the player base p servers aren't. Also, it's a cash grab as well as a non-impact experience. There's nothing revolutionary other the tweaking of a few values to make it more difficult. It makes it less enjoyable. The scarcity of loot can be difficult and unsettling with the timeframe. It's a fantastic idea, but no world buffs are great! People were already calling for it before classic was even the norm. This is the time!
Well, new instances and other all of it is basically retail. It's like making an "alternate timeline" by adding items to classic that isn't already available in retail. ....I am able to comprehend rule changes etc. But adding areas, bgs, etc. could buy Burning Crusade Classic Gold mean that you are entering retail territory ....