Don't cling too much to version numbers It's true that "beta" usually indicates that the software is feature complete, however, this approach does not always fit very well to computer games (in return that would mean we couldn't even add more features after the beta stage, which would be a pity). Nowadays it seems that many developers and companies take a looser approach on that word anyway
So when Rising World goes into beta state, this doesn't mean that it is feature complete. It will be more of an indicator that the most important features are already implemented and that the game offers "full and entertaining gameplay" (not only for builders). In other words, at this point, RW is going to offer more extensive survival and exploration elements. In addition, updates will be more polished (we will do more extensive tests before releasing an update), so there is a lower risk that a new update doesn't work or breaks the game, but in return, it may take longer until a new update is available (that's why we don't want to go into beta until the gameplay is more entertaining, especially for survivalists).
We will keep the game in beta state until all known bugs are fixed and ideally all features from our features list are implemented (unless we discard a feature for a good reason). If people are still playing RW when it leaves Early Access, we will continue to work on the game. There had been many community suggestions about certain features which may get implemented after the 1.0 (seasons, extensive npc interactions etc).
But what happens after Alpha 1.0? Probably we will just surpass the 1.0 mark, even though the game is still in alpha. So maybe the game will be in alpha until version 1.1, 1.2 or 1.3