All four of those technologies have become prevalent within the past few years, and it took me no more than a couple weeks to grasp the fundamentals of each and start being productive. Sure, I spent time Googling and reading documentation, but I also didn't write code that would be a great candidate for the DailyWTF.
So yeah, I love being an old fart in his 40s. You can hire that twenty-something kid for half my salary, and he might put in more hours (most weeks I top out at around 45), but I can tell you I'm way more productive today than I was in my 20s. And I can learn those "new tricks" just as well or better today.
 That's when I was in my 20s and 30s, not during the 1920s and 1930s. Now get off my lawn dammit!
 Yes, those are huge over-simplifications, to the point they kind of make me cringe, but the point is these new technologies all have parallels to something older.