It is expected to be released this year, probably in the summer. But we don't know the details yet. The current rulebook is no longer available to order in quite some countries (
viewtopic.php?f=1&t=33536), so that could mean that GW will no longer be printing this book because the new one is coming soon(ish).
I've heard rumours that maybe something will be revealed at Adepticon, which runs from Thursday 22 March to Sunday 25 March. So if you're on the fence, I'd at least try to wait for that.
Finally, while we do know for sure a new rulebook will be released at some point, it doesn't necessary cover all (or any of?) the (Hobbit) profiles. I'd love it if they released one big book with everything in it, but that's not what they've done in the past. It's possible that the There And Back Again book will still be relevant (at least for quite some time) for the Hobbit profiles. And it will probably stay the only source for the Hobbit campaign scenarios. Though I do wonder what they'll do after the current Hobbit rulebook has gone out of print as it contains the first couple of scenarios for that campaign.
There And Back Again doesn't actually cover any new rules, just scenario's and profiles. I would expect at least the scenario's to stay relevant (if you're interested in them) and quite possibly also the profiles, at least for some more time than just this year.
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