i think the only reason mlb hasnt become like euro soccer is because of the roster requirements that the players (quite rightly, imo) want to get rid of. not the draft per se, but the eligibility rules and 6 years before you hit free agency.
if they get rid of that or significantly pare it back and allow players to hit free agency at a much younger age, then without a salary cap you'll see all the young players bought up by the big clubs. and if that happens i think you'll see more stratification because the rays and other such teams wont be able to control players long enough to compete. that's my thinking. even with a draft, if you only control a guy for one or two years and then you have to pay him, only the big clubs will be paying.
baseball free agency is fool's gold now because youre buying guys at the end of their primes for the most part. and dumping 10 year deals on 32 year old players will kill you.
if you have a cap, those deals will dry up.