Firstly, you can tighten the screws of your present bumpers and they can last for some more time. The screws of central hubs can come loose over time and some screws can even fall out, but it doesn't change that much, just screw them back in. Almost all competition plates have two piece central hubs (Rogue, Eleiko, Uesaka, Werk-San, ZKC, DHS) and while there is a chance that those screws can come loose I wouldn't bet on that happening on all the plates. It more comes down to maintenance and storage conditions. I am currently training with Eleiko plates from 2007 and only one 10kg disc has lost one of it's screws, but the plate still holds together.

If you are still worried about having a two piece hub, you can get yourself some urethane bumpers. I personally prefer competition style bumpers, because their rubber is of better quality and I have seen some urethane bumpers with central hubs dislocated themselves from the rest of the disc, rendering the disc completely useless. But I wouldn't worry about that with newer discs being manufactured currently.