Sony Europe has announced that PlayStation Network will undergo maintenance on Monday, December 9 and will run eight hours through Tuesday, December 10. Below is the official tweet, though no firm details were announced.
Heads up > There will be Network maintenance on PSN – Monday 9th/Tuesday & 10th Dec between 16:00 and 00:00 GMT. Thanks for your patience.
— PlayStation Europe (@PlayStationEU) December 6, 2013
No solid details have been provided, but if past maintenance periods are anything to go by, online gameplay should remain available for anyone who has recently signed into their PSN account and have their authentication details cached. Those who haven't, will likely be unable to sign in to their PSN account or play games online.
Earlier this week, Sony reset the passwords for a number of PSN accounts due to "irregular activity" on the network. It's unknown what next week's maintenance will bring, but it could be some extra precautions.