The information was revealed by Monolith Productions community manager MonolithJared in a Q&A thread on the Middle-earth: Shadow of War messageboard. Several fans asked if they’d be able to trade in currency earned in-game while offline, and the rep replied that, “at the moment, we require an internet connection.”
Now, before you get too worked up, I don’t believe you’ll need an online connection to play Middle-earth: Shadow or War – it’s only required to access the market. That said, you can earn in-game currency offline, so you really should be able to trade it in offline. Hopefully Monolith rethinks this entire system before launch.