The problem with estimating future prices is that the variables are unknown. Of course, you could plot a range of scenarios, and guesstimate how prices for each might turn out for each different scenario. Then you could determine how much to invest in either gold or btc or a balance of both, as pdclenton suggests.
In these scenarios you have to predict how local markets will be formed; for example, we know that btc gets a good deal of value due to it's use in underground drug markets. If SHTF, then drug purchases probably will be made locally. If that were to happen btc would lose some value.
Next you have to balance scenarios; suppose btc goes down b/c people buy recreational drugs locally in trade for food, but also consider that other factors could drive btc up at the same time, such as the local warlord demanding that cash be kept in "his" bank.
I will restate that a serious investment will be in personal supplies. In the US, there is either a 7 day or a 3 day supply of food is kept at the local market. If the food supply chain is distrupted, and if you DONT live on a farm, you are going to need food. Think along the same lines for water storage/supply/purification. Medical supplies, toilet paper, and alcohol. Alcohol can be used medically and recreational, and I have quite a few bottles of cheap ass vodkee set back. Weapons to keep your personal and trading stash secure. Last note. Dont sell ammo unless you absolutely trust the buyer.
You have a whole range of how bad SHTF could get, and additional ranges of other problems/opportunities that develop.