I would argue Nintendo will get more money from people buying this and the copious amounts of 3DS software available than a one-time purchase of the NES Classic.
I would argue there are more people left who want an NES Classic Edition than people who don't already own a 3DS and would specifically purchase New 2DS XL and copious amounts of new software.
There are also multiple similarly-priced competitors for playing 3DS games available on the market right now, where NES Classic has no (legal and legitimate) competition.
I like the 2DS XL design, but find the pricing borderline ludicrous. There is no moderately priced entry into the product line outside of the (clearly marketed at children) original 2DS console, and as someone who need to replace his handheld before playing again I find that hugely disappointing.
In Canada you can pay $110 for a 2DS with game included, $200 for a New 2DS XL, or $240 for New 3DS XL. Those are all of the options. The latter two don't come with chargers or games. Paying over $200 for a system that has been around since 2011 (yes, it's been improved since then... but how many games use those improvements?) is ludicrous.
Remember the Black Friday sale where they brought out a cheaper 3DS unit? I was so excited... of course, there was virtually no stock provided and I've never seen an in-stock non-XL unit since that date.