יאיר האט געשריבן: דארפן מיר זיין אפגערוקט נישט מער ווי געציילטע טעג.אגב, דאס איז גרויסע נייעס פאר מיר. וואס וועלן די חרדים טון ווען פסח וועט אויסקומען אין די גרויסע פרעסטן? וואס וועט גובר זיין, די מסורה פונ'ם לוח אדער די מסורה פון די גמרא?
You're right. According to this we moved 9 days in the past 2000 years. I remember from years ago that it was more like a month, but I don't know and I don't know how this coincides with the date of March 12 to APril 18 for Adar that Yidel brought (I don't know how to calculate the average Jewish month according to the solar calender
Someone with more knowledge needs to help us out
Your point about the very far future is really amazing. Artscroll gemara mentions somewhere in what year Pesach will come out in the winter according to our current calender
A 6 month shift should be like in 40,000 years from now. But it wil take less than that for the gedolim to start worrying about it. If Moshiach is still not here and the world would still be something like it is tday (not very likely) you can expect a big schism within ortghodox judaism over that issue.