I don't get why people always want new boards. The more you separate subjects from the OT, the more it dies
The OT will continue to flourish, irrespective of whether or not new boards are added. The addition of a music board and outdoor board haven't diminished the activity of the OT. It's still prospering.
Quite honestly, I would add three new boards - Religion/Philosophy, Technology, and Health/Fitness. Major categorical subjects like this need a dedicated forum of discussion. Doing so fosters more substantive and focused discussions. Additionally, each board tends to have its own "regular" posters and ultimately develops into a unique sub-community, engendering and enhancing sentiments of solidarity among the more active posters.
The OT will always have a seemingly infinite number of thread possibilities, so it will never "die" out. You'll have threads like this, And this. And this...
The dilution of the OT has been taking place for the past decade, yet it's still the most active board on the site.