Exactly how it is going to work is not 100% decided yet.
But most likely it is something like this:
# Standard random startpos maps can be played with teams, which will then be random positioned.
# Mapcontrolled startposition maps can be played with teams. Here the teams positions will be decided by the mapcreator if he/she has setup this for the map (the same way as you set specific starting locations you can then choose which team the color should belong to), if nothing is chosen the teams startingpositions will be randomized among the diffrent available mapcontrolled startpos - i.e. default for all current Beta3 maps.
# Scenario map, here the teams are setup by the mapcreator. The idea is it should be possible to define like 4 players on one team against 1 player etc. Will see how it works out in the end though
- so no new maps will be needed, however if you want to controll the teams starting positions you will need to update your current beta3 map, but it will be a very small and quick update.