@Drabslab, The "linking" system is already in place through the "Friends" feauture, Planner wise. Also in MRA Mobile routes of friends are easy to open. So my guess is, that when a Navigation button is added to a route overview, exactly what you want will be reality.
We have to consider the integration of Planner Mobile and Navigation. A lot of what is already in there will be applicable to Navigation too when it's integrated. The more I think about this, the more I see the advantages of integration, where I was reluctant about that at first.
I like this suggestion of driving friends routes without importing them in your own account.