What about when Fiat becomes obsolete/completely devalued? I feel that we are,as crypto enthusiasts, and supporters of quality blockchain technology, creating a new ecosystem to use in place of the old one, which will eventually collapse.

Through all the research I have put together it shows me that when the next economic collapse happens, its going to happen rapidly, and markets are currently showing evidence of a major correction is imminent.

Then wouldn't all of these coins have significant value?

For instance, when a major correction happens like the last one in 2008, people scramble to find the most secure place to store their value/currency, back then it was in your safe or under your bed, now its cryptocurrency. The next time we see a major economic correction, people are going to scramble into crypto to store their value. This will cause the value of those cryptocurrencies to skyrocket, then those people are going to want to spend their highly valuable coins on things like they normally would, but if the value of fiat disappears no one will want to throw it away. They will then decide to spend it on one of the many platforms that will be getting developed, helping develop better quality coins/ecosystems, and especially if it is working better than the system they were using before, because inherently we all know the current one isn't working.

This is why I believe that his estimation is actually being modest, think about the amount of industries in business right now, then multiply that by all of the possible users of each industry and that will give you the estimated total users of steemit in this proposed future.