Huh? Aren't you saving only $20 with two game vouchers, but you'll have to pay $20 for an online subscription to get the vouchers? Nintendo is just giving back the money that they stole, so that shouldn't be met with gratitude.
Got my subscription for free with the Amazon prime deal, which I also got for free, so I have very little to complain about xD
Not knowing if all future releases will be included is the only negative, however E3 should clear that.
Finally 49.99 games shouldnt be included here, theres no benefit, it even makes the process of buying them more complex
You can only buy vouchers until July 31st, 2019. Plus it has to be a pair of them (and is probably restricted to only one pair per account), so you'll be paying $100 upfront. Vouchers have to be redeemed within 12 months of purchase date.