I don't know when LX took over the last time the MUC route and I disagree with you at least on the summer schedule. They increased their presence in GVA in a quite healthy and cautious way. Whatever is planned has surely undergone a proper evaluation potential and revenue-wise. If anything will be cut in summer, I stand corrected, but I certainly believe that they base additional CS1/3 to cover these flights as well.
btw. including those two new and the ZRH flights, the overall LX destinations from GVA will raise to somewhere around 40.
Last time LX took over GVA-MUC was in April 2016 and lasted until March 2017. It had the effect of leading to the following routes being cancelled: CPH (5x/w), BEG (2x/w), SJJ (1x/w). Routes with reduced frequencies: BCN (9x/w to 4x/w), NCE (9x/w to 5x/w), DME (8x/w to 7x/w), LCY (18x/w to 17x/w). LX also at pretty much the same time got rid of the Q400 operating to LUG and also cut ALG and SKP at the end of the summer schedule in 2016.
The problem back then was that the introduction of MUC left LX at GVA with 6 aircraft of which 3 were dedicated to MUC/LHR/LCY and therefore 3 left to operate about 20 or so destinations - it led to basically an incoherent schedule on the other remaining destinations.
What I am told by internal sources is that LX had a lot more planned this summer at GVA. The initial plan was to receive 2 not 3 aircraft (which is what is happening here with MUC/FRA) - the net result being that a number of planned (but not announced) new destinations won't launch as planned this year. Apparently the decision to switch MUC/FRA to LX came from LH and came very late. The initial impact being that some destinations should have had more daily flights (MAD, BCN and possibly NCE should have been 2x daily this summer).
That said there are still some gaps in LX's summer schedule from GVA with changes still to come (including some schedules that seem wrongly loaded) and things seem to change very quickly (which is why we've seen 3 route announcements in the space of a month for IBZ, JMK, BDS, ALC, FAO then LCA and now FRA, MUC). Route count right now from GVA is 45 routes and should get LX to around a 20% market share.