Personally, i would wait. Keyboard problems are enough of an reason to wait.
Probably will not see an March update, more likely it is in June. But the update will (most likely) bring 8th gen 6-core CPU's to 15" MBP's.
So in a long time, this is going to be significant performance boost. But, ofc if you can't wait. Then 2017 MBP would be a huge upgrade from what you have now.