It was all over social media yesterday, but in case you missed it, WotC announced some serious changes to Standard and Modern.
Effective Date: January 20, 2017
Magic Online Effective Date: January 11, 2017
Emrakul, the Promised End is banned.
Smuggler's Copter is banned.
Reflector Mage is banned.
Gitaxian Probe is banned.
Golgari Grave-Troll is banned.
The list of all banned and restricted cards, by format, is here. The full list of cards banned in Modern is here. The full list of cards banned in Standard is here.
Next B&R Announcement: March 13, 2017
Expect to see some serious decline in the prices of these cards and a number of cards featured in decks enabled by them. I can guarantee we'll have some great Insider tips along these lines, and some ideas for where to invest from here.
If you sell now you're only going to get garbage prices, so I would hold on to the banned cards specifically. Emrakul, the Promised End definitely has casual and Cube appeal, and Smuggler's Copter is a great Cube card that sees play in Frontier for whatever that's worth. Grave-Troll will take a big hit due to the fact that it has become rather obscure in eternal formats, though it should only get harder to come by as time passes, and I would only sell if I needed the money.
At any rate, I believe that these changes are net positive, and I'm excited to see how they play out. It's also worth noting that in addition to announcements prior to every Pro Tour, there will also be a second announcement made five weeks after every Pro Tour on that Monday. This will be a great way to keep formats from being broken for long periods of time after the game's greatest minds break them. As such, I would keep my eye on the new Saheeli Rai combo and whether or not it destroys the PT, lest it gets banned after the fact.