well said OP. mythic coins in a 15k stash is worth the upper end of the spectrum for sure~ although overall mythic coins have been in a strange stagnant spot.
I'd say it's still 50/50 at this point to say what will happen over time obviously. I would say yagrush will always be worth the 150+m so the coins have that going for them for longterm value at the very least. even if this does happen there could be a job adjustment, new gear later on down the road that makes the multihit weapon relevant after skirmish wreaking them etc. who knows.. And then i could very well see mythic coins becoming something overlooked as far as guesstimating the supply pool will be available to dip into. all the sudden if 10-20 people on the same server decide there gonna build a mythic at the same time you bet the price of alex would be quite prone to climbing very quickly.
personally im holding out on my next mythic. I have built two mage mythics. At the moment I would love to build a more 'fun' damage dealing weapon. So obviously koga to get the most worth for the numbers, but i'm still reluctant because i'm a warrior fanboy and would love to holdout to be ontop of a different power streak if/when the tide turns. atm I'm holding onto about 10k alexandrite myself not sure if i'l actually use it for a nirvana/koga.
I think it's a good idea to be about 50/50 invested atm if your not sure but still know your gonna want one if nothing changes