Remember when Jace, Vryn's Prodigy // Jace, Telepath Unbound defined Standard? Remember when it was an $80 card? The perfect storm of being hugely popular in Standard and being a mythic from the least opened set in Standard in Magic Origins will do that. Casual demand for the two mana flip walker in addition to fringe play in non-rotating formats kept the card hovering around $20 even after rotation, though the card may see significant growth sooner than later.
When I first heard about Hareruya holding a Frontier tournament, I had no idea what it was or if anything would come of it. Since then, this style of event has received press on The Mothership, and Face to Face Games in Canada has also started running Frontier events.
A couple stores in Minnesota have started to host Frontier events, and players have been asking us about hosting Frontier as well. The format is picking up steam, and being discussed frequently on Reddit and other online platforms. It's still unclear whether this is the next Tiny Leaders, the next "Over-Extended", or somewhere in-between, though near as I can tell the format is already attracting more attention than Tiny Leaders, likely due in part to the format following traditional deckbuilding rules.
Jace was a good long-term position given that he draws demand from multiple formats, though Frontier would be the format that causes him to see four-of play in multiple decks. The more time passes, the more successful frontier seems to be, and while I'm not ready to tell you to do something like stock up on Siege Rhinos, Jace is a solid pickup given that minimally he's a good long term play.