I find it worth mentioning myself that they are starting to pave the way for a lot of the stuff on the list within the next several Alphas. They are working on new character models and animations, a new clothing system, and vehicles in the next update. There also has been talk of weather effects and surviving against the environment. It's also a bit distant, but NPCs might be on their way as well.
Personally I think by the time they reach Beta they'll have a lot of the original stretch goals done. The only things on here left for Beta I see is the workshop and map creation tools, the story, professional voice acting, and Oculous Rift support, and maybe a character creation tool if it doesn't make it in Alpha (The current character creation looks like presets and clothing). It actually makes me curious what they plan to do in Beta if Alpha does end up finishing most of the list. In fact, I didn't know there was going to be a Beta, I thought the use of the term "Alpha" was a misconception (still kind of is, and Alpha is technically in house production and testing), but it appears there will be more in due time.
I will however mention that a road map would be nice to see, as I'm not sure what the entire direction of things are, though the Pimps are making good progress and adding in things that weren't planned as well. I kind of feel like I'm going from update to update, which is fine, but knowing where the game is going long term if they have any ideas on that would be nice.