The competition is growing every year, we can't expect every changes on what will be the consequences. On the positive side about eth, the span of 10 years is enough to consider maturity stage if it's price so I would have to expect $10k achievement. If we're able to reach that stage, I think long terms holders will have the perfect time to harvest their fruits of labor.
$10k for 1 Ethereum? I dont think that would ever happen. Ethereum does not grow that quick to reach 10k in 10 years. It took three years to increase ATH from 1400 to 2000, and now it looks like Ethereum has run out of power to grow. If the story repeats, than in about 3 year Ethereum would cost $3k, and by the end of 10 years about $5k, but only if they would fix fees issues and release some major upgrades (like Ethereum 2.0, but not like Constantinople).