Couldn't agree more. In the months leading up to the TC, 19s have become revitalized and are in an amazing state to carry on and grow from here.
Obviously, the prize, the title and the epeen was a huge driving force; and assuredly, many recently active members of the community will scurry back to their mains or whatever niche occupied their time before the lead up to the Cup. I don't think anyone has fooled themselves into thinking that level of activity was sustainable for the long term; particularly once the summer has ended and a large chunk of the bracket finds itself back in school. However, it doesn't seem unfathomable that 19s will persevere as it does time and time again.
With that being said, there remains a potential for 19s to fizzle out as well. One of the factors, as Agonist touched on, is the migration to other brackets as seen in previous years. 20-29 to a certain degree, but seeing as how that bracket thrives at any hour, day or month, it's impact is negligible. The main culprit last year, and potentially this year again, is 39s. Let me start by saying that this is not meant as a snub to said bracket's organizers or community members (a good number of those being 19s as well). However, it seems that similarly to last summer, 39s will ride the coattails of 19s success/activity, dividing the community and ultimately negating the momentum created in the past months. What I can recall from last year's revival was that the week had it's designated nights for 39s, which 19s did briefly still get games on but they were of a *** awful quality with long queues; that shifted into 19s not getting pops on those days at all; then longer queues during the rest of the week; and finally, culminating in 19s ceasing to pop without a truly organized effort. Then the kicker, 39s die out and neither bracket is active.
Let's not let things repeat themselves. That's all I'm saying (although the wall of text above says otherwise). I think the bracket is in a better state than the situation I detailed about last year; no xpac, no huge game changing patch, and the TC was a overwhelming success this year and only in it's infancy last year. I do truly hope those of you that love your 39s will indeed get pops and have the chance to play your dusty twinks... just not at the expense of 19s.