I suppose it's how much they can do with the code they have isn't it?
From what I understand the maps on Shenmue are separate to the areas you can go into hence the need for loading. Now I'm no expert at all but wouldn't there have to be some loading time for the console to access the data etc? Now this may well be sped up by the power todays consoles have now & the GDEMU example (I'm jealous and want one of those) shows that it can be sped up but needs to be there.
My ideal would be 3-4 seconds per area. If they make it so you can go into shops without loading then great but if not then I can't see the loading screens being an issue. I quite like them