capital one x discover merger: how will this hurt/help us users?

some questions I was wondering if any of y'all are more knowledgeable to comment on:

1. why are they merging, and how does this help or especially hurt customers?
2. will this affect my current account or card? do i need to do anything?
3. are my rewards or cashback programs changing? will there be new fees or higher interest rates? does this mean fewer card options or perks?
4. should i cash out points or rewards before the merger?