Also: yes, get more feathers (duplicates) instead of wasting tickets, UNLESS you know that you are going to miss out on a lot of the next (New Life Festival) event. The more feathers that you get, the more bonus entries you get into the other ongoing ESO Sweepstakes event.

Note: the in-game ESO help implies that you CAN get a second mount if you get enough feathers, as long as you evolve them differently. I'm assuming that the event tickets will also be needed in later 2019 events to buy "berries" of different types, although the actual berry acquisition mechanics have not been given out yet.

10 tickets = 1 feather

4 different feathers = 1 nascent indrik

x tickets = 1 berry

1 nascent indrik + 4 different berries = evolved indrik (and loses you the nascent one)

The first evolved form to be available will be the dawnwood indrik (the green one you can see next to the event NPCs tent). This will require 4 dawnwood berries which are not currently available but which will be purchased with event tickets. (We have been told how many tickets they cost but I can't remember.)

3 other evolved forms have been announced - black, white and gold, and will be available later on. Getting those will involve making another nascent indrik to evolve.

So yes, eventually, there will be a use for more than 4 feathers and some people have been buying extras in anticipation of this. The best option now however is to spend 10 tickets on the next feather as soon as the New Life festival starts, and then collect more tickets from the festival