Most things will work for awhile. As technology moves on, though, software companies will eventually stop supporting XP versions of their products.
I have my nephews XP from 2001. It has not been used, and therefore also not updated with automatic downloads, since about 2003. When I tried to update it this past summer, I couldn't. The version of XP on the pc is so old it can't process the updates and web pages don't load correctly. If it had been automatically updated all along, it would probably work just fine now. It doesn't matter to me - I got it for my Grandson (10) who is always fooling with the settings on the computer and going places on the internet he's not supposed to go. He can play games on it and change settings (and then forget what he did) to his hearts content, because it's not hurting anything/anyone but himself if he wrecks it. It has no internet connection available to it where I put it. (Note: He has Aspergers syndrome and truly doesn't understand why he shouldn't do what he does on the computer. That, coupled with being intellectually very bright can be a problem.)
Eventually, you will have the same kinds of problems with your XP, but it should take a couple of years to reach the state that my grandsons' pc is in.
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Your biggest short term issue will be security, especially once the security software makers decide that they don't want to support XP anymore. As long as everything else is working on your pc and software security still supports XP, you can use the XP. After that, it's time to get a new pc.
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You can use software that is loaded locally on your pc, like Word and Excel, until the pc breaks down. ("Locally" means that you have your own licensed copy of the software on your pc AND you can use it without ever turning the internet on.)
NOTE: While you may still be able to run your pc well enough and connect to the internet after security software no longer supports XP, I don't recommend that you do so. Hackers will be quick to exploit that 'opportunity', and nothing on your pc will be safe from them.