Currently Kovri seems to be made for monero, but has there been other announcements of others implementing it into their cryptocurrencies? If Kovri is java based, how would that work if a coin is built using another programming language?
Kovri is a C++ implementation of I2P which is Java based.
Kovri is no more than an I2P router. If another coin has wanted to use I2P they could have just bundled it into their node. To my knowledge, none actually has this level of security.
Kovri is open source, and could therefore be used or forked by anyone.
Read more on kovri website