Yes, it is discontinued.
The manufacturer has displayed a zwave plus replacement at some tradeshows, but it has not been certified yet and there is no place to buy it.
There are a few possible alternatives depending on exactly what you need.
The Leviton VRSC4 is a very similar 4 button mains powered device, but it is also due to be discontinued soon, and only a few dealers still have it in stock.
The remotec zrc90 is a newer battery powered device with eight buttons that is about the same size as the SC7 and is quite popular if you don’t need a mains powered device.
These and other devices are discussed in the buttons FAQ