If we use the example of Arduboy 1.0 to assess a best guess on a release for Arduboy 2.0, we would probably resolve that the time for that release could be m months, where 4 < m < ∞.
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I would say if you want to learn C/C++ and draw things to a screen with little bootstrapping on the hardware end, then purchasing an Arduboy 1.0 is a good idea.
Sometimes, when it comes to learning, I like to get started ASAP if I'm after a concept. Other times I want to go through the entire process with no assistance and discover things for myself. You may have your own approach. Whichever way though, it's best to just get started.
I wouldn't personally wait on the Arduboy 2.0 if I wanted to start tackling some of the concepts, but it also doesn't hurt to wait to place an order for the 1.0 until looking through the Github repository for Arduboy, and maybe seeing what it's all about.
Maybe look at the community booklist and skim a copy from a library or online. You can also write C/C++ without the Arduboy and compile programs for you own machine using your console or terminal, but it is a tad more difficult to draw "images" using C/C++ to a screen without the Arduboy.