Well... I am not so sure.
(1) I am not aware of any Win95 emulators (not that I was in need of one, and not that I have enough interested in this to search the web for one... But to my knowledge, the software that came with my USB 2.0 DVB-T receiver would not run on any system of today. Luckily, this doesn't worry me, as this software was crap, anyway, and I've never used the stick with Windows. I mention it just as an example. When cameras of today are replaced by something completely new, such as the technology that Lytro uses, formats and software of today will become obsolete. How quickly that will happen, and when it starts... only time will tell.
(With Linux the DVB-T stick runs as fine as ever, BTW).
The reason you don't see a win95 emulator is two fold:
1) most applications that run on win95 will run on the latest version of windows
2) for those that don't, install win95 on a spare machine or in a VM
As for your example, yes, there are certainly pieces of hardware and associated software that may be more difficult to get working.
That said, let's not loose sight of what we're discussing here. We're NOT talking about a day-to-day machine here. We're talking about the theoretical situation where ALL current software has lost the ability to read a CR2 file, and the only solution is to run some ancient software. In that case, all we are interested in is "resurrecting" this lost format and converting it to something "current". In that case, creating a VM or running an emulator is a small amount of work to get what we want.
Our concern is never getting the images back, not editing on an ancient platform.
(2) Even if there are emulators that are able to run the system and the software, you use now: Can you be sure you can connect all your storage devices? What this means is, that every once in a while, when connector standards evolve, new drives need to be purchased and huge amounts of data have to migrated to them. Noone expects to see USB 2 compatible devices in 20 years, I guess...
Prior history says yes. 20 years ago is 1994. The predominant storage formats were 3.5" floppies and CDROMs. Both are easily read by modern machines with either a preinstalled DVD-ROM drive, or a USB-floppy drive (have one in my desk).
Go back 30 years and things may get a little more dicey. 5.25" floppy drives are much harder to find.
All that said, yes, if you leave a bunch of backups in a box for 50 years you MIGHT be in trouble. That's why I recommend people do what I do: live backups. Keep your data up on modern media. As the media progresses bring your data with you. If it is REALLY that important to you then it's a small price to pay.
My backups started on ZIP disks and CD-ROMs, moved to DVD-ROMs, and now live on hard drives, drives that all get updated in various degrees. My live backups are current as of an hour (cron job running every hour). My offsite (away from my home) backups are at most a month out of date. My last tier is at most 6 months out of date, and is secure in a vault.
Am I crazy to put this much effort into it? Perhaps, but my photos and other data are that important to me.