LH-Group responded quickly to Ryanair's intentions on CGN-SXF - before the Ryanair flights have even become bookable germanwings/Eurowings have today started to sell CGN-SXF and STR-SXF (3 daily on both routes) - an airport that germanwings last served in 2012 I believe. That is in addition to the existing flights to TXL from those cities, that will be maintained at existing frequencies.
Looks like the battle is on.