What do you think that might happen with Bitcoin if no scalable solution becomes accepted?
I said this more than once. If bitcoin doesn't manage to scale this year, and ethereum will keep developing and getting adoption from institutions and corporations as it curently does, there's 50-75% it will replace btc by the year's end. Mark my words.
And what awaits then the mass owner of Bitcoin coins, if they all expect a Rainbow future for their capital. This does not affect the price of Bitcoin in the coming years?
It would of course, at a large scale. If bitcoin would never scale, some other coins might take the spot who already has the lead in terms of adoption and development e.g. LTC or ETH. However, what coin would replace bitcoin that I have no clue about since I'm still wary about ETH rise and LTC seemed to be too far off the charts.