McAfee said 1 million when it appeared ridiculous to say that, problem with his attempt at an estimate was the timing was far too narrow.
Schiff I've heard state a price of a few hundred which means he admits there is some idea of purpose, the price being much varied from that would tie in to his greater criticism of dollar so he argued himself into a corner on that one with lack of imagination.
BTC is doing better then many expected and its still never enough for some, mostly people are impatient. We only have to know that BTC continues to outperform and Dollar prospects have been notable worse and increasing in decline if anything since the inception of BTC.
Right this moment, BTC put in a triple bottom around 92900 and price is moving upwards there. The best guess is based off an increasing ascension in the lowest prices, less showy then the highest prices but more accurate to say.
McAfee was interesting because people thought his predictions are as crazy as his life stories, but I think someone like him who understands so much about technology had a point there. The problem was that he was pumping these shit coins with his twitter account and that made him untrustworthy. Yet, doesn't mean his prediction was unfounded.
Schiff has been going back and forth as far as I know, but his main point was that bitcoin is worthless, but gains value from the greed of people and fulfills nothing else but the purpose of a financial gambling instrument. But what can you expect from someone who is neck deep invested in gold, seeing that bitcoin's market cap is growing at unprecedented rates while gold is essentially stuck and can make perhaps 2x or 3x if you wait 20 years.