I really like Runbow. I really like buying physical copies when they are available. But I've already (quite recently) gone out of my way to buy the game on the Wii U eShop in order to support the developer... so much like the Shantae physical release, this news pretty much doesn't matter to me.
That said, the 3DS release might convince me to buy if it's got some unique content to make it worthwhile. A portable version might be different enough to justify a purchase... although being New 3DS exclusive and (probably) lacking multiplayer aren't really selling points.