Well specifically T-Mobile did not announce its hacking incident, it was actually a matter of third-party sources making
their findings public. Initially T-Mobile then went into denial mode, then after more and more research and sleuthing was done (again by third-party analysts and news media) T-Mobile finally admitted a breach had indeed occurred. But it also lied about its scaled and number of people affected, only recently now coming clean (relatively) about the whole debacle. The point being, this is just another, typical scenario. There's a public revelation about some issue, the targeted company may or may not live up to it even when there's documented evidence, and then the next news cycle just comes along. We, the public, get screwed and they just keep accumulating more money. So don't hold your breath waiting to find out if MetroPCS is or isn't involved, the odds aren't very good there is going to be a definitive answer being made public at this point.
If anything be sure to log into your MetroPCS account and change your password and/or passcode now. No sense waiting for an announcement, be proactive about accessing your account. And at a deeper level, freeze your credit reports:
https://www.nytimes.com/wirecutter/money/how-to-freeze-credit-reports/
This is something you should do anyway, no matter if your carrier has or hasn't been sloppy with its own security practices. A major aspect to T-Mobile's screw up was all the personal data they retained and how loosely secure it was archived -- things like people's credit history might be needed when they apply for an account but there is no viable reason when T-Mobile needed to keep all that info afterwards.
