What is the upside limit? The available btc seems to constitute a limit. How can we estimate the proportion of the btc which might flow into XMR? Consider that maybe 10% of bitcoin core own some XMR. Maybe twice that number of btc holders want XMR, and maybe they will risk 20% of their btc... By slight of hand I conclude that XMR might be able to command 4% of btc market cap in the long run, just on the basis of current bitcoin holders, without a huge change of circumstances, given the right amount of time.
Suppose non-bitcoin holders want XMR. Unless they are in the u.k. almost surely they will sign up for some btc/fiat exchange, take days or weeks to verify, buy some btc, fumble around, and eventually get on poloniex. (Watch poloniex wallet addresses!). I expect a lot of lightly crypto-exposed people who sat out btc to buy in over the next few weeks. But btc has had years of recruitment, and the absolute numbers are small, relative to the current holders. Probably new crypto users are less significant to reserve use, and more significant to DNM traffic stats, and will make themselves felt on the traffic and speculation driven by that traffic, rather than on the volume of btc they spend on XMR.
Overall these vague and fuzzy reasonings are consistent with other vague and fuzzy reasonings which I expressed elsewhere, that I expect XMR to trend around $25 in 2017...in that case conditionalized on 10% of DNM traffic being denominated in XMR.
Usually when SWAGs derived by different methods coincide, I give their common estimate a lot more weight. Not twice as much...more like the second power on some unbounded likelihood scale. Funny, I haven't thought about the probabilistic logic of that before. I should do.
That's short term thinking in my opinion.
You do not need bitcoiners to adapt Monero to reach parity with bitcoin. All you need is stingy Monero sellers and greedy junkies.