Do I need to activate my new PS4?

My old PS4 is bricked, and not under warranty. I got a new PS4, but it said I couldn't activate it without deactivating the old one. I have to deactivate the old one remotely though, and doing so would also mean i need to deactivate my in use PS3 as it only says 'deactivate all'.

I'm the only person in my household who uses the PS3/4 and the only one who uses my psn account. Do i really need to activate the new PS4, and, would deactivating my PS3 do anything untoward or bad? I don't really get what this whole (de)activating malarky does.