The main problem you will face with type of workflow is the merge.
How do you merge a a changed architecture back to the baseline?
RAS will not be helpful with the merging process. That is going to be a manual thing, because you only want to merge the new changes tot he baseline, and make you sure you don't overwrite previous changes.
Especially with a lot of projects going on in parallel, you'll have a hard time managing it all. (that's why tools such as Portfolio manager exist)
The way it could work using RAS is to have different repositories for each project, and one repo for the baseline.
You upload the baseline to RAS, and download a copy of the baseline in the new project repository.
Then when the project is finished, you'll have to export the relevant part (as xmi) and merge it back to the baseline.
Then upload the new version of the baseline to the RAS.
There is very limited support for merging model content in EA, so this will be a very costly and very laborous process.
You couldn't pay me enough to do this type of work

In my opinion this is bound to fail.
I've seen many organisations setup a system like this (with or without RAS) and they all start out with good intentions.
But then after a few years, projects get finished, but never merged into the baseline, the baseline starts to get out of date, etc...
Geert