Timed exclusive need not necessarily have a specific end date, prime 1 can drag it along and end it whenever they see fit. This could go even up until just before production release. Or they could only distribute a certain amount of DXS to worldwide retailers and keep the remaining DXS exclusive to their store and at their own discretion. Or they can do a bit of both and determine maximum leverage based on sale figures.
Bottom line, I think ordering DXS from a local retailer would be pretty safe (as long as it's DXS, not DX). Prime 1 have already caused division between Reg and DXS purchasers with the added trophy and props mask, I highly doubt there going to cause anymore further division. Pretty sure no additional items will be added to the DXS anyway, the amount of bells, whistles, easter eggs this statue has... its already as loaded as can be. With the exception of a mouth portrait (though that will operate on a different spectrum i.e if made, very likely we'll have to pay for it so doesn't apply to the above).