I'd imagine that UK and US Tolkien releases would be identical going forward for non mass market editions and will be sold as HarperCollins editions in HMH markets.

Updated with News that sale has gone through

Houghton Mifflin Harcourt Enters Into Definitive Agreement to Divest HMH Books & Media Consumer Publishing Business for $349 Million

Learning technology company Houghton Mifflin Harcourt (“HMH” or the “Company”) (Nasdaq: HMHC) today announced that it has entered into a definitive agreement to divest HMH Books & Media, its consumer publishing business, to HarperCollins Publishers, a division of News Corp

https://www.hmhco.com/about-us/press-r ... 36&utm_campaign=corporate