Americans have to file taxes with the IRS regardless of who is paying them and where the company is based. There are tax breaks available (on taxes owed to the US) if you are living and paying taxes in europe to avoid double taxation for the most part. It makes the paperwork a little more tricky but it’s still done frequently and isn’t “very unlikely.” The most difficult part isn’t your american taxes it’s making sure you’re paying taxes correctly in your new country. It will make it easier if you work for a multinational company (like Schneider Electric USA, for example) where they already know the ins and outs of taxation in both countries, but I’ve known people to do this out of smaller companies as well.