I think they will eventually move it to the Basic Drink Mixer when they notice but that's just a guess at this point.
No matter which way I look at it, I fear there will be unhappy players
If they leave the recipe where it is now, players may feel the need to build more Ice Cream Makers to speed up their goal progress. If they move the recipe to the mixers, there will inevitably be players who have already used gifts and requests to build more ICMs that they would no longer need.
I hope if the team
does move the recipe, they give players free parts for the new appliances. This might soften the blow for those that 'wasted' their parts on an appliance they no longer need.
I've asked a Mod to forward the matter to the team so hopefully we'll get a response before the end of their business day.