It's likely that MS would continue their barebones "Arcade / Core" SKU when Natal comes out. There is a reason they are holding the line on its pricing now when they could obviously lower it right now.
I imagine this is why they are rumored to be introducing a new $400 SKU (it would keep the average sales price inflated).
Assuming this comes out in approximately 1 year (Fall 2010)
I think the pricing will be
$149 xbox arcade (no HDD / no Natal)
$199 - $229 xbox 120GB elite w/ Natal bundle (I am assuming the cheapest bundle with Natal will be the exact same price as what I project he Wii will be selling for)
$249 - $299 xbox "Super Elite" 250 GB or larger HDD + Natal bundle (perhaps with an additional extra included and will be at the price point of the cheapest PS3.)
