Can I discard high end shipping boxes, and still sell in the future?

Yes, but you will get 10 cents on the dollar instead of 15 cents on the dollar.

I learned the hard way to keep the original boxes wherever possible.  Not only do the original boxes perfectly protect the equipment and have styrofoam inserts that perfectly fit and therefore protect the equipment, but to have expensive gear, especially speakers, packed in new boxes and bubble wrap is pretty pricey itself.  And if it isn't done right, you get a mess when delivered. That has happened to me twice, (receiving and selling) when I lived in a condo with minimal storage space.  Now that I am in a house, every box has a nice storage spot on shelves that I built along the ceiling of the garage.  I'm not sure that I would pay less without the original packing, but it is definitely a selling point.

For $300.00 a month I would not $3600 a year, are you going to lose $7200.00  off the average secondary market price if you sell in 2 years? I fortunately have plenty of storage space, being am empty nester, well for now see if I have any boomerang back.  

I would add: original packaging is generally safe but easy to use new packaging that is just as safe. It just takes time and material, and likely ends up a bigger volume due to double boxing which will cost more. I boxed porcelain figures that you could drop from the 2nd floor without a scratch. Lastly, most plastic used for packaging are very harmful, never decomposing staff

I'd say sensitive equipment boxes and packing should be kept for shipping unless selling locally. I'd never discard the box and molded styrofoam inserts for my tube integrated amp.