Yeah, Nvidia probably announced today (with only you noticing) that their next cards after the currently unnanounced 50-series will be out soon. Makes sense.
This is just a trademark filing. Not even by Nvidia themselves, but a third party. It's very normal, and does not in any way mean that the 50-series will be shorter then normal. If these last few months is a indicator of anything, it's that jumps between new architecture/ graphic card generations will be longer in the future.