Following its launch in Western territories on 12th October 2013 — alongside Pokémon X & Y — the 2DS has sold (as of 31st March 2014) 2.2 million units. That's not too bad for a hardware iteration targeted at a rather specific demographic and not given the most high profile of launch campaigns. As a budget tablet-like alternative without the 3D effect, it appears to have enjoyed a solid start at market.
It looks like Nintendo is planning a tweak to the manufactured unit, too. An FCC filing (Federal Communications Commission) in the US (spotted by myce.com) was submitted in late April — with some documents just made available to the public — and is currently in progress, which seeks approval for model FTR-001_-01; this is a variation of the standard 2DS model that is attributed as FTR-001. As you can see in the letter below, the change is to the CPU to adjust a security function.
This sort of occurrence is likely fairly common in terms of model updates and tweaks to hardware, but it's interesting to see a 2DS submission this early that appears to have the goal of tightening security on the system.
Hit up the second link below to see all of the documentation related to this filing.