According to the announcements and the game guide, the town and hero skins are 'unique'. 

Does this mean they are unique to each season and will not be available again once that season is finished? 

Being in the league of conquerors, the max amount of Runic Coins it is possible to get is about 2,2M as far as I have been able to calculate so far. Going up to league of Masters increases the amount of Runic Coins by 15-20%, but increases the points needed for checkpoints 200% up to 1000%(!) making it seem like a very bad deal to upgrade. 

Getting extra coins from getting top position on events is also just about pointless to try for as the change in league levels now puts you up against players with higher influence and deeper pockets. 

What exactly is Plariums plan for who are supposed to be able to get the new town skin without spending huge amounts of money? 

Why set the requirement to league of conquerors to obtain runic coins if you can't actually get the top item by normal play? 

If the only way is to get into a higher league, it just means you are forced to spend money to complete events as far as I can see, which I guess is the whole point anyway.