[RedDevil]

Ehm... from that article:

The process is pretty simple. At a wastewater treatment plant ... sewage is separated into liquid and solid waste. ... microorganisms are added to the mix. These microorganisms break down the solid waste, creating biogas, about 60% methane and 40% carbon dioxide. Then, workers filter out the CO₂ and add water vapor, which creates hydrogen and more CO₂. They extract the CO₂ again, and voila: pure hydrogen.

Mixing methane and water vapour does not produce hydrogen and CO₂ just like that.
If it were that simple we would already be doing that from straight methane.

I bet the Mirai can use methane as a fuel instead of hydrogen. It would be easy enough - methane is less volatile anyway.
Burning it produces some CO₂, of course, but that would otherwise be released in some way too (like if the H₂ scrubbing did work after all) so it should not matter.

I guess Toyota prefers profiling the Mirai as a hydrogen car rather than an methane car. Which is a pity, as straight methane seems more easily providable than hydrogen.

If we accept methane cars and infrastructure the sky is the limit.
If we persist in using hydrogen (and having the capability to use that, including the special tanks etc) the cost will stay prohibitive.
The Toyota Mirai will remain a mirage and the Honda Clarity a rarity.