How many years/copies depends on a lot of factors. the 7545 is good for *up to 200,000 printed images a month* (I wouldn't suggest it as a routine though) But say 100,000 images a month (way more than realistic for anything but a huge office or medium print shop) that is 1.2 Million images a year.
10 years and 10 million is not an outlandish expectation.
Like anything though, It will be outdated long before 10 years. It's 5 years old now (launched Oct 2010). Doesn't have native MOPRIA or Airprint (Mobile printing/scanning is already here, and not shrinking) Direct scan to/print from Dropbox/OneDrive/Office365/Google Drive isn't there (To be fair, this tech has only truly come to Xerox in the last month, so its early days for sure)
Parts for old printers are not easy to source, so if you needed a part besides the typical consumables, getting those parts can be tough. It could very well be 8 years from now, out of contract, you take a flood/lightning strike/power surge/brownout that takes out a power supply or circuit that is no longer made, or very expensive. Would the device at that point be worth the cost to repair?
As security requirements tighten, features get unusable as well. Most of the SMTP servers recently updated from SHA-1 to SHA-2 encryption over TLS. This killed access to any printer that doesn't support it. If the printer is still in active development, it gets added/fixed, if it is not actively developed, it may not. From the company perspective, they make nothing from you doing a scan, it's entirely a freebie for the end user. The fuser doesn't click so Xerox gets nothing. They will likely decide it just isn't worth the cost to implement a fix.
Long story short would be that the device will outlast the users need for it in most cases. 10 years from now there should be no need to even have printed output. Something like E-ink will have entirely replaced it if not mobile devices of some kind