Well, you kind of answered your own question.
So just imagine what about 100 professional devs in a mature gamestudio that's been around for 20 years can do when working full time.
It is hard to imagine before we see some screenshots, but I am assuming the planets today are rendered using the same technology they will use for surface landings. I noticed some visible detail popping even when looking at the planet from afar, meaning when going gradually closer it will suddenly change dramatically as a more detailed version of the planet is shown.
Detail popping is what these kind of procedural engines often suffers from, and they have to be finely tuned to ensure immersion is not broken because a big mountain suddenly deforms in front of you to a more detailed model. Outerra and Infinity does a great job in this respect, details are revealed smoothly as you close in.
But, it is way too early to compare. The graphics in the game today is so different from what a stroll on the planet surface would look like.
Another aspect is vegetation, water, different types of rocks, snow, lava, atmospheric effects, procedural cities... The list goes on and on. It might take more efforts to generate and render a good looking diverse planet than to make the entire rest of the game. It is easy to ignore a lot of this and just do some simple rock formations and throw in an atmospheric shader, so I am curious about their level of ambition.
I do hope they have some super talents like Ysaneya on their team though. Team size and experience is one thing, but procedural planet rendering is a pretty advanced topic and needs highly specialized talents.