I would say that all entry prices remain the same: $349/399, $549/599, and $10,000/12,000. Pricing further up the range could change depending on how the band offering is revised, but I don't see the starting price with sport bands changing.
While I see the band mechanism remaining unchanged, I don't see them making the second gen Watch available without a band. If you have an existing band you're carrying over to the new one, then you'll just have to buy the sport band configuration. Apple has already made it clear how they want to sell the Watch by not letting you configure any band with any watch at purchase, so I don't see them offering the option to have no band. Besides, the sport band is only $49, so the most you'd save from this option is $49 ($300/350 for Watch Sport, $500/550 for Watch). I don't think not offering this will be a dealbreaker when it comes to people upgrading.
I also can't think why the existing Watch would continue to be sold when the second gen arrives. Apple already offers three very distinct lines at three different price points. It has been rumored that they may be introducing a tier in between Watch and Watch Edition, bumping it to four lines. Offering the existing Watch Sport, and also perhaps the Watch, would mean producing five or six different models. It would also just totally crowd the sub-$1,000 range. Plus, a $249 first gen Watch Sport makes the more expensive models an even harder sell, and at $299, the price difference isn't meaningful enough to warrant its existence. It is also quite clear with the way that Apple has marketed the Watch that they want to avoid getting into the tech specs to make the product seem less like a "gadget", and upselling people from the first to the second gen would require them to delve into the whole "twice as fast, GPS, front facing camera, blah blah..." angle.
