You are correct in that there is nothing you can do at this point other then pay out of pocket. I think that you are worrying for nothing as right now there is no problem at all. If the delay is MX Delta has a few options of what to do in your situation. They can put you on another carrier to get to your destination (least likely) or do as you described above. You would get a hotel voucher, meal coupons, transfer to and from the hotel and airport and do the flight the next day. Delta in this situation will also normally give you some miles for your inconvenience. The last option I can think of is that Delta might attempt to re route you via another airport (example PDX-DTW-AMS) if your flight is very late and you will miss connect. Right now I think you will be fine and that you are worrying for nothing. Let us know how it turns out.