Movie WI: The Star Wars series doesn't have screwy numbering

Fairly simple, but I think interesting. What if George Lucas had decided not to make The Empire Strikes Back "Episode V" (hence retroactively making the original Star Wars "Episode IV") but instead had stuck to a more conventional numbering-in-order-of-release regardless of chronological position? So you'd have:
Star Wars <Episode I: A New Hope, I guess, again retroactively>
Star Wars Episode II: The Empire Strikes Back
Star Wars Episode III: Return of the Jedi​
How could that affect what direction the Star Wars series takes after RotJ? Might there be no prequels at all, given that Lucas hasn't effectively locked himself into making three? Or -- here's a thought -- might there be more than three prequels?
 
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