It wouldn't be impossible, but it'd be a bit harder to pull off. And at least based on the coding experience that I have (sophomore in college for a Computer Engineering Software degree; experience with Unreal Engine 4 & Unity; have coded in Java, C++, C#, etc.), having the console be ARM would be more of a benefit to Nintendo than it would be a detriment for third parties. I may change my tune if things get dicey as my programs grow more & more complicated, but I'm just going off of my current experiences with programming.
See above. I'm not an expert just yet, but I'm on my way there.