Buy Fallout 5? I don't really have an opinion. Say yes? What if it's even worse than Fallout 4? Say no? What if it's actually good? I'm always on the fence, it's safer and smarter that way.
I honestly believe that Bethesda developers enjoy the kind of game Fallout 4 is, and it just so happens by pure coincidence that it's the same kind of game that can be easily marketed. The publisher (Softworks) and develoepr (Game Studios) in this rare example seems to be well-acquainted with each other (Howard and Hines), so this is likely the case.
Hell, it could even be not by coincidence, but possibly because the devs at Bethesda are the same kind that buys into the AAA hype and enjoys simplified, streamlined action games, which would be hilarious irony if true.
If it isn't made by Obsidian, then my answer is Hell no. Considering how many copies FO4 sold, I don't think there's a snowflake's chance in a volcano that they'll return to the old formula. They'll turn it into a single player MMO even more most likely.
Or, you know, an
actual MMO.
In my opinion, I hope there's a parallel here. To me, Ubisoft Montreal (the guys who make the Far Cry games) do a much better job than regular Ubisoft when it comes to design, presentation, plot, story, etc. (or at least they did until they made that piece of shit Far Cry Primal) So I'm hoping that Bethesda Montreal will redeem old Bethesda, much like Ubisoft Montreal did Ubisoft.
Far Cry Primal wasn't really a piece of shit (though I haven't played it so what do I know) from what I've heard, but really, just more of the same. They didn't fuck it up more but they didn't add anything to the formula either - the modern industry's pattern. Why innovate and risk losing profits when you can do the same thing again and cash in on it?
I wouldn't really expect Bethesda Montreal to "redeem" anything. I expect that the games will become better optimised and less clunky at a whole, but there will be no steps made towards New Vegas' path because it is simply inconsequential to their profits. We'll probably get Fallout 4 again, with a slightly different plot, a slightly different setting, better graphics and less crashes, and about the same level of consistency and depth.
No no no no no...NO. True RPG or GTFO.
I know what you actually mean, but arguably, New Vegas was in no way a "true RPG" either, so in that case you would be waiting for a direct successor to Fallout 2, in which case you'll probably have to wait for all eternity.