Is the price rise related to the change of PoW again?

Try bitmain 

Most nodes will run in dual mode with both Kovri and a regular IP. People who want can go full stealth (network monitoring can only tell that you are using i2p, not that you are running Monero or anything else through it) will be able to run only Kovri, but there are tradeoffs and most people don't need that. Also, anyone wanting full stealth probably currently probably uses at least a VPN and/or Tor, etc. and won't be on that map now. So the map won't change much.

I heard Kovri is forking from the I2P network and will only carry Monero traffic.

Most nodes will run in dual mode with both Kovri and a regular IP. People who want can go full stealth (network monitoring can only tell that you are using i2p, not that you are running Monero or anything else through it) will be able to run only Kovri, but there are tradeoffs and most people don't need that. Also, anyone wanting full stealth probably currently probably uses at least a VPN and/or Tor, etc. and won't be on that map now. So the map won't change much.

Wouldn’t this create the “optional privacy” problem that Zcash and other coins have? If you have the option to turn on full stealth it would single out those who are, right?

Yes i think so too, but if you basically use the same protocol as i2p, the network doesn't know you are using it for Monero. What's the real tradeoff?

I think he's talking about the proposed fork of the C++ Korvi I2P as opposed to the Java based I2P. They would not communicate and therefore the Korvi nodes would all be Monero nodes.

Read this.

https://github.com/monero-project/kovri/issues/1000