Assuming what you say is true, and that a crash occurs in say a year from now, followed by a spike of the VIX to 100 which is roughly 6 times where it is today. However if the Vix averages around where it is now and contango is as steep, this would translate to a monthly loss of 15%. Compounding that loss for a whole year will leave you with 15 cents on the dollar that you have invested. A VIX spike to 100 coupled with assuming that VXX follows suit, would result in VXX rising to approximately 90 cents. So even with a VIX spike to 100 a year from now, you would not even break even on your current investment!
Monthly loss is more like 8-10% for VXX. It gets cut in half every 6 months, the rest is the ups and downs of VIX. For example, if the VIX doubles between now and March, and we havea VIX of 30 ... VXX will be in the 30s. If VIX doubles sooner than that, VXX could march up to around say $40 or $44.
If VIX is at 30 a year from now, VXX will probably be ... $15/sh.