Been looking at 3DS and Wii U releases from 2013-2015 and I saw an average of 10 exclusives for Wii U at retail and 14 for 3DS, not counting digital games.
If the library is shared, let's say that 20 games are made per year for Nintendo systems exclusively with little to no droughts based on the devs costs slightly evening out.
(Would be cool if someone found a list of total retail games for both platforms per year, couldn't find a good one)
The portable games get a big bump to an almost HD device but the console's development costs go down slightly and they already have established HD experience and dev tools at their disposal.
This should help with launch and to have something consistently coming out.
One of the biggest issues with Nintendo is that they push completed games back to the holiday season to sell more leaving droughts, and they space out releases thinking the fans have both systems which leaves some months where the 3DS or the Wii U feels under used.
I think just with that they fix a lot of their issues and could make consumers happy even if at worst case scenario the 3rd party support is a repeat of this generation.
If they can see a big improvement over 3rd party support, and get major titles like DQ, FF, CoD, Star Wars, etc, Nintendo could have something pretty special here and either way I think fans will be pleasantly surprised.