You're probably right, although I'd probably go short on hydrogen in trucks. It seems hard to store, transport, requires a new infrastructure, etc. I expect they'll use this new fangled technology called 'diesel'.
I'm surprised when I don't hear more about the lower hanging fruit. The fact that Fedex/UPS haven't gone wholesale into electric is telling at this point, I expect they'll do it when some spreadsheet shows 10 cents in savings companywide. The champions for electric trucks should push for trash pickup, route sales, local delivery, etc. and not bother with long haul for now.
You could argue that a good place for hydrogen would be non-electric trains. When the bugs get worked out of that perhaps long distance trucking might have a chance.
edit: as an aside, I can see where large scale fleet decisions might be held back by fear of technology change. You'd sure hate to buy thousands of trucks only to have them made obsolete by some sort of large underlying change in design that's a no-brainer.
It wouldn't surprise me if there isn't a certain braking effect on vehicle purchases generally because of the advances in EVs. There's a righteous fear in being an early adopter.