While we're not sure about any specific launch dates, we are expecting the GTX 980 and GTX 970 to launch very soon. The latest clue is that MSI is teasing the design of its GTX 970 on Facebook. Teases of this caliber usually only happen close to the launch.
The card is definitely recognizable as an MSI card, as it follows all the design cues of previous cards. Note, though, that this card is carrying the new TwinFrozr V cooler, which has a number of small improvements over the older design. We can't be sure about all the changes yet, but the cooler does have a large fin array, heat pipes, and two 100 mm fans.
The GTX 970 is expected to carry 1664 CUDA cores, along with 4 GB of memory accessible over a 256-bit memory interface. (We're speculating a bit here though, so take these specs with a grain of salt.) What is almost certain is that the GTX 970 will be based on the new Maxwell architecture, which will allow it to provide more performance per watt. If you look carefully at this card, you can also see two six-pin PCI-Express power connectors, which is a little less than the 6-pin + 8-pin design on the GTX 770.
Stay tuned for the actual launch.