Thanks for your reply.
The peer that hosts the mint is selected by the configuration agent from among the super-peers. The simplest method is to take-turns round-robin. The duration of the mint responsibility is a parameter that can be adjusted. Given that the mint hosting schedule can be efficiently published in advance to all peers, then the mint hosting duration could be anywhere from 10 minutes to perhaps one week.
But what are the (objective) criteria by which the mint role is assigned? My worry is that there is no valuable/scarce resource necessary to become the mint and therefore control the network...
The most valuable ressources (for an attacker) seem to be "node-stake" and the quantity of nodes since everyone seems to be able to become a super peer no matter of his stake size (correct?). Isn't this much easier to achieve than pure stake?