Is there any academic research or theories about what future events and metrics will most influence BTC's long term valuation relative to fiat currency?
There are some research papers out there, including about bitcoins economical viability. A wonderful (a pleasure for hours) and fairly complete list can be found on the wiki. A random chosen abstract:
Bitcoin has emerged as a fascinating phenomenon of the ﬁnancial markets. Without any central authority issuing the currency, it has been associated with controversy ever since its popularity and public interest reached high levels. Here, we contribute to the discussion by examining potential drivers of Bitcoin prices ranging from fundamental to speculative and technical sources as well as a potential inﬂuence of the Chinese market. The evolution of the relationships is examined in both time and frequency domains utilizing the continuous wavelets framework so that we comment on development of the interconnections in time but we can also distinguish between short-term and long-term connections.
Have fun! :)
None as yet. It is pure speculation, and in any case any study of such a kind would have and even chance of being completely wrong. Nobody can see into the future.