I agree, although what you get from Tek/Agilent/LeCroy is still a markedly different product than what, e.g., the SDR there gives you:
-- First and foremost, you wouldn't find anything from Tek, etc. without a proper data sheet containing things like noise figure measurements, intercept points, etc. Agilent seems quite good about that, Tek is usually OK, LeCroy is perhaps sometimes kinda minimal.
-- Calibration/NIST traceability. This is a big deal for many companies, and the products aimed at the amateur radio market typically don't offer it.
-- Ethernet connections. I like USB as well as anyone, but I'd have to admit that if I were building an automated test system (and this is where the big bucks in test are -- not just a few pieces of equipment here and there for design engineers), I'd consider Ethernet rather more reliable than USB and insist on it. Everything from Tek, etc. has this option today, whereas only some of the second-tier units do.
I think the big guys are already adapting to a large degree -- but they're never going to hit the price points you'd personally like, I expect, if only because their cost of business is too high. The big guys might lose a lot of the low-end market, but there's still a lot of technical hurdles at the mid- to high-end that you just don't see "garage shops" being able to pull off -- there's a reason the vast majority of digital scopes designed in China don't go beyond about a GHz, you know: At that point, the off-the-shelf parts you can use start to become slim pickings, and it pretty much requires a fair amount of DSP work to obtain reasonably-flat frequency responses. I.e., it becomes much more complex than just throwing together a 200MHz scope using off-the-shelf ADCs, an FPGA, some memory and an ARM microcontroller.
---Joel