What are you expected to do with MWBCs?
AFAIK, there aren't any 2-pole AFCIs (combination type) on the market.
Combination type being acfi/gfci?
My understanding is that there are, in fact, 2 poles now available.
Pricing on the other hand is quite profitable for the manufacturers.
I was quoted $111.69 for either a 2p15 or a 2p20 Siemens from a supply house the other day. No 2p20s in stock, but like everything else, they can have it in a day or so.
I really believe that in the theoretical world these kinds of decisions will help prevent fires, and thus save lives. In the real world, however, it is going to further drive a wedge between the contractors who will do things up to code, and correct, and the contractors who will come in and do a quick job without inspections, and leave who knows what kind of mishaps behind.
Maybe not so much in higher end areas, but in lower income areas it will force people to either not do the electrical work, or have someone do it cheaper(ie cut out the costs like arc fault breakers.)