It will still run. The current versions of your software will run.
You won’t get security updates. People will go on figuring out new exploits, and you’ll be exposed to them. It’s not just businesses that need to worry about data protection, what’s in files on your computer that you wouldn’t want spread to all and sundry? What about if someone was logging your keystrokes – passwords and all?
Even putting all that aside, end of Microsoft support means people making software won’t feel compelled to support it either. Things like Garmin Express – it supports XP now, but it won’t always. You’ll buy some new bit of hardware that needs software on a PC to work, but it won’t run on XP because they never intended it to be supported on there.
Given how cheap hardware is these days (and way faster than XP-era stuff) there’s not much reason to stick with it now.