That is my plan, I have (had, you have to let it go) an old account from when it was a just username, never bothered "updating" it to the email account, I tried to convert when Microsoft said they were dumping all the old accounts, but the process was not working and I quickly decided I don't actually want a Microsoft account. At which point I decided that if I ever wanted to play again I would just do so sans account.
Which raises an interesting question, If I legally have a license for the game but they shut off the license servers, is it actually copyright infringement? (or piracy as people like to call it because copyright infringement sounds lame)
They will certainly argue, and win, by saying that for legal mumbo jumbo reasons, you only have permission to play it in the exact ways they say you can, and if you already bought the game, but they say you can't play, then it's illegal to play.
Which is why coming at this from a legal perspective a farce. Most of the world is like this, actually. You can assume that if some action brings money to large corporations then it's legal and if it takes away their actual or potential revenue then it's illegal. Go with what you feel is morally correct.