YES, old save games will not be compatible and will be lost with the new patch, because a lot of new variables, visible and otherwise, were added with the patch. Sorry.
The 1.5 patch is nearing completion and after a bit of testing, will be available within a short time. This patch will be mostly bug fixes, tweaks and a few new features. Once the basic game gets ironed out and solid, then a 2.0 patch will follow with more new features, probably in mid-Feb.