There is no point investing in an interim technology when a more mature technology that is superior in every way imaginable is already in commercial use. The biggest hurdle to hydrogen is never the prime mover but always generation and storage. No viable R&D will come out of this. There is only one very niche use for hydrogen ICE and that is powering and heating spacecraft with a hydrogen wankel engine which can be very compact and lightweight (and burns pure oxygen and does not worry about NOx). At least Mazda got it right with going Wankel.
Lucky TMC, they can just fire all their experts since they have this forum.