Per this site, yes, but one issue with oneplus with previous phones has been upgrade delay. Most OP3 reviews mention the company's track record on upgrades.
So OnePlus has plans to update to 7 but but they just don't have a solid timetable. And unfortunately they don't have the greatest track record with timely updates. However, as Jerry said so eloquently, I don't think the update will be super important for features and things as far as the phones daily functions.