I'm sure there will be a work-around ... i.e. a mod that allows you to go back to ID numbers, but say, putting a letter in front (like Broonie has with all the kits - I for Item, B for Block, etc.). The mod then interprets this for the MC code by converting it back to the new ID Naming system.
No doubt this is going to cause a lot of problems with mods that interact with other mods.
Personally I think they should have just kept the ID codes, added the names, and then make mods use their own ID system say with a 4 or 5 digit code in front of the ID number (registered with Mojang so that it will be unique to a mod).
A 4 digit code of upper case, lower case letters and numbers would give a possible combination of 14'776'336 combinations - a 5 digit code gives 916'132'832 combinations ... I think that's plenty of room for mods