How concerned should we be with API v2?

On another post (https://developer.personio.de/discuss/619e19852f376303215b2c32), @Oleg Fedoliak informed @Nitin "there are plans to introduce a new API v2".

If API v2 is on the horizon, how much sense does it make to develop for the current API?
How long will API v1 be supported?
Might v2 require large changes to digest the response?
Is there the possibility to be involved with API v2's design, development, and/or testing?