Why would you automatically assume that every team would just call up a minor leaguer for the 26th spot? Seems to me like that's about as likely to go to a free agent as any other. Speaking of which, there are a couple of pitchers still on the market that would make great 26th men if the rules were effective immediately.
By definition, anyone not in the majors is a minor leaguer. So, anyway you slice it next year there will be 30 guys in the majors that would otherwise be in the minors.