Replacing SOD with fetch (handling JS library dependencies - *in the future*)

Question

Anticipating a future, I am experimenting with User Custom Actions in the new Document Library View Microsoft has so kindly provided to the First Release Office365 tenants.

Since there is almost nothing SharePoint left (no JSOM, no SOD) I am trying new technologies to get JS library dependencies working.
Note that Microsoft does load RequireJS, but if they can get rid of the SP Object, JSOM etc.
I am not going to rely on anything but a modern Browser

fetch is Chrome and Firefox only for now (april 2016) http://caniuse.com/#feat=fetch

fetch('https://.../file.js')
    .then(function (q) {
        return q.text();
    })
    .then(eval) //for those who think evil! It does the same as the (old) DOM abusing below
    .then(function(){
        //do stuff
    });

Since this is all Promises, this would make loading multiple libraries a breeze

Any cons in using this over:
(good old abusing the DOM for no reason other then get a file loaded/executed):

var element = document.createElement("script");
element.src = "https://.../file.js";
element.load = function(){
    //do stuff
}
document.head.appendChild(element);