1. Bitcoin Gold fork is very badly prepared and (was referred as) is a joke. Information about the fork is lacking. no replay protection.
This is why it almost seems to function as an advertisement against hard forks. It makes them look like altcoins. It's even possible that Bitcoin Gold is a joke. Supposedly there will be replay protection, but it is not present in the code yet.
2. Segwit 2x fork has no replay protection, which will cause double spending to a certain degree. This fundamentally challenges Bitcoin's principles....which is to prevent double spending utilizing Blockchain technology.
It won't cause double spending, because that phenomenon refers to a single protocol/blockchain. It doesn't apply here because no BTC is actually being double spent in a replay attack. Coins on another chain are being spent in a "replay attack." The lack of replay protection in Segwit2x will make such attacks possible. Basically, if you try to spend B2X, you may spend BTC at the same time. If you try to spend BTC, you may spend B2X at the same time.
3. possible Bitcoin Unlimited fork (sorry I have yet to read more about it) may cause chaos to the Bitcoin network and there may be many versions of the bitcoin blockchain....
Bitcoin Unlimited is irrelevant now. Nobody will be following any BU chain. Their supporters all seem to be supporting the Bitcoin Cash altcoin or the Segwit2x fork.
Due to the above reasons, are the fundamentals of Bitcoin indeed challenged by the upcoming forks?
Many people have said that "Oh, we have survived the Bitcoin Cash fork, it will be the same this time, just HODL"
but it may seem that this time the value of Bitcoin could be really challenged?
Many people have said that "Oh, we have survived the Bitcoin Cash fork, it will be the same this time, just HODL"
but it may seem that this time the value of Bitcoin could be really challenged?
I would say that the fundamentals are certainly challenged by the forks, but not for the reasons you mention. The biggest concern for me is that there is no network agreement around Segwit2x, so it is sure to cause a split. If the companies backing it are successful in co-opting Bitcoin and overtaking the name/brand/ticker in the face of widespread opposition from users, Bitcoin's "decentralization" will surely be questioned. And the prospect of a real, permanent network split between the legacy chain and the Segwit2x chain could damage the price, too.