I manage hundreds of indesign files. When I upgraded from CS6 to CC2014, each time I opened an indesign file, I was forced to "Save As" and navigate to the folder the doc was stored for all of them vs just hitting save. I get that... Its a giant pain in the *** but at the time, I assumed that it made sense since I upgraded to CC from CS6. But i never thought that I would have to do that whole process again with this CC2015 release that I downloaded yesterday. This is a giant time suck. Please tell me that something exist to keep me from having to do that all again? If this is going to be the case with each release, I won't upgrade next time. its too damn much trouble.
Leave the files you're not currently using in their current format. When you need to make some active changes on the file(s), then re-save them in the new format. This will work with smaller numbers of files.
Another approach is to leave files in their original format. This can require having multiple versions of InDesign on your computer. To do that, I recommend the utility called Soxy from Rorohiko:
It opens files in their correct version. There is a beta version of Soxy that supports InDesign CC 2015.