The underlying technology is changing so fast (ES6, web components, mobile web, etc.) that it's going to make upgrading an obvious choice even if it involves relearning a lot of stuff.
and also do you think they'll continue with the 1.x releases? since so many developers have already invested time and effort on their webapps and shifting it to an entirely new framework (read release) is a major cost to pay..
https://www.youtube.com/watch?v=LG9VkCDbte0&feature=youtu.be
They say the exact plans for how long they are going to support 1.x won't be finalized until after 2.0 gets released, so that they have some idea of how difficult it's going to be to migrate.