Yeah, that was weird wasn't it? the fact that of the 4 people who represented China in the world junior table tennis championships, 3 of the 4 were all lefties....
Anyway, I don't think you have to worry about penhold disappearing. The Chinese National Team wants variety. They don't care which Chinese player wins as long as one of them does. Therefore their strategy, it to play into the competition players of different styles. If you happen to have an advantage against one style and beat that one player, they still have some security because the other player's style is completely different. Its part of the reason why during the WLQ and Ma Lin dominated era, one of them always reached the finals and won (the main reason of course is just that they are insanely good but...) The two of them had nearly polar opposite styles. One was about super quick speed and spin, and ending the point quickly, while the other was about power, and the longer the point lasted the greater the chance he would win.
Given this, the Chinese team will probably always want to have a penhold player on their national team, because most people just aren't used to playing them, penhold represents a total different style, because of its better service, better and therefore emphasis on the short game, and the Reverse backhand offers a ton of spin in flips.
I think in general penhold is harder to master, and therefore the Chinese team usually keeps their penhold players hidden away more, until they really reach an adequate level and then they are finally brought out into international play. I mean look at Xu Xin and Wang Hao. We basically didn't even hear about them and didn't know they existed until they finally arrived on the international scene in their first tournament. And both were 18 or maybe a little younger when brought out into the open.
So I don't think we should worry, some penholder we might not even know about will randomly appear out of no where and be good.