The price could go up that much but I would suggest be careful about it when that happens, if the price goes up anything above 15k there will be a huge gap in the bottom which means it could literally freefall back down under 10k and that would hurt many investors. That is why I highly suggest people to buy now and sell then instead of actually buying then, if you see bitcoin going up to 15k or more than do not buy it, it could still go even higher but that is a big risk compared to right now.
I am not saying bitcoin won't reach 20k or higher, it will but if it does a sudden move without closing the gaps then it will eventually fall which will be another bear run for months for us, it should slowly go up and down in order to reach highers while closing the gaps in between.
Without Altcoins, Bitcoin is not of great value and its price cannot be much higher than $ 10,000. I think the price of Bitcoin will decrease.
May I know what is your basis on your statement?
I just see the opposite happening because without altcoins, there will be no more competition in the market, hence, bitcoin would easily rise even higher than it has previously reach. Bitcoin is not viewed as a successful payment system because compared to the fiat payment system, they are more faster, bitcoin as its price getting higher, it's not good anymore for small transaction as the fee is high and the network congestion is one of the problem.
Bitcoin now is heavily invested because people are transferring their money as bitcoin is more promising due to its limited supply that could result to a higher value as the demand increases.