Just look at how far it's come already.
There was once a time before modern engine technology when a really smooth running engine was one of the most coveted and expensive features of a luxury car. Companies like Packard found that more cylinders made for smoother running, and started making V12 engines. So, in 1930, Cadillac started making V16s, because it just had to be the absolute best. Cadillac was a seriously big name in top-tier luxury cars in those days, and most featured bespoke coachwork.
Of course, as we all know, the company would get lazy, and as recently as 20 years ago was something of a joke; making giant pseudo-luxury land yachts for old people who didn't trust foreigners. But the degree to which the company has been turned around, and in a relatively short period of time, has been genuinely astonishing. The meteoric rise hasn't been enough to dethrone the Germans just yet, but Cadillac is the most profitable part of GM right now, and the public is still acquainting itself with just how much things have changed. Change has come fast, but it's not possible to do it overnight.
So the question now is where does this all go? Can Cadillac ever overtake the Germans, and if it does, then what? Is it ever possible for Cadillac to return to that prewar status, where buyers faced a real decision in choosing between a Cadillac and a Rolls-Royce? This would mean succeeding where Mercedes failed with Maybach, and this would certainly be a tall order. We're talking some time into the future with this, but being so profitable, Cadillac has access to tons of GM development money. And with the new CT6 flagship already on the way, an incremental move upwards seems like it could well happen.