The on-prem vs cloud argument is sufficiently tired. Obviously you should do the math and figure out what's best for you, but that's not really related to AWS releasing new VM types.

If you're running on AWS for whatever reason, i3 VMs are great news.

If you're using it for three years, then you'd take an RI and it'd be 60% of the cost. You also don't have to worry about failed parts, hardware monitoring, racking, power, etc, plus the skills required to manage same.

Yes it is more expensive than buying your own hardware, but I thought we all understood at this point that AWS does a little more than just give you an empty server and no additional services.

You can't really do that kind of math without using AWS incorrectly. The reality is that you won't run the instance on AWS for 3 years. You spin it up when you need it, and you kill it when you don't.

There will be some instances that you'll run 24/7, but this shouldn't be the case for your entire fleet if you're on AWS.

I seriously doubt you could do that. Those SSD's are ~1.5k each right alone and the power/infrastructure to keep it running reliably with a fat connection to the internet isn't cheap.