I so much dislike the idea of the Traveller verse being played with D&D 5e rules, that getting all my concerns/criticisms down would result in a very lenghty and not so readable post. Just need to say, my players and I spent way too much time trying to find SciFi magic in a bottle with d20 (d20 Modern/Future was my 1st buy after a decade+ away from TTRPGs), that I'm not keen on exploring the genre with 5e. Fortunately, not much long after d20M we discovered Mongoose Traveler 1e and really enjoyed it - still homebrewing for those rules with Cepheus Engine.
We tried Babylon 5 d20, 1st d20 Star Wars, Gamma World 6e, Interface Zero d20 and they all fizzled. And more recently Esper Genesis and Ultramodern 5e, which we didn't care for. For my SciFi lovin players and I, classes along with their restrictions just get in the way of what's fun about playing and evolving a SciFi archetype in a futuristic setting. And the core d20 dice mechanic, can often seem too swingy for such settings. Admittedly Star Wars Saga, True20+SciFi and Starfinder were decent, but IMO they're exceptions and quite different from the D&D rules they were derived from.
Not to be overly negative, but over the past few years I've developed a dislike for the biz practices of Hasbro-WotC. So, I'm not thrilled to hear about a quality TTRPG publisher like Mongoose partnering with them. One of my concerns is that this might detract from Mongoose's efforts on some of their less known TTRPGs. Personally, for me it doesn't matter that much - armed with a couple of core books I'll homebrew to my hearts content. But IME TTRPGs that aren't well supported, tend not to be known or attractive to gamers and makes it hard to find players interested in playing them.