I've got to assume Tesla will make good on their promise to include a UMC.
Just an interesting aside for anyone like me who has ordered a UMC - mine came with a superfluous CCS Combo 2 Adaptor (really only useful for people with old model S/X). When I asked about it, Tesla Sales realised their "might" have been a problem with the order. On closer inspection, it came with 8A and 12A tails, which is also not the current type. I am awaiting more information from Tesla, but assume they'll swap it, or send me the correct tails.
tl:dr If you order a UMC, check carefully if it's the right version.