The experimental already gives a good clue as to exactly what is going to happen. If you deconstruct an MK2 miner which you build on the live version, you get back 1 portable miner. The new recipe requires 2 portable miners. If you then go ahead and build an Mk2 miner and deconstruct it, you will get back 2 portable miners. This implies that despite having the same name, same mesh and texture, theses are actually 2 different buildings with their own unique ID, properties, and maybe, their own coding. This makes it very plausible to assume that old production lines are going to keep working just fine, but that new production lines would have to use the new recipes.