I think the only reason they introduced the 8 was to have a new phone ready for sales ASAP knowing that there would be delays with the flagship X.
This could definitely backfire on them since the changes between the 7 and the 8 appear to be minimal when factoring in the price. Might as well keep or get a 7 if you can't afford or wait for an X since they will be cheaper than the 8 as you stated. Only time will tell.