Right now we are in a very interesting time in the development of cryptocurrencies, while I believe in bitcoin we are still not sure if it is going to be the dominant cryptocurrency in the future, segwit was a step forward and it decreased the fees somehow, if the LN is really successful then bitcoin will be the dominant crypto for decades but if it fails then another crypto with superior technology will have the open door to try to take that place.
Yes. It's a very interesting time for cryptocurrencies indeed.
Ever since SegWit was activated last year, Bitcoin has seen a sharp decline in fees, as well as increased user interest. -snip-
Exactly. Bitcoin has grown strong over the years, which makes it practically impossible to become dead anytime soon. With the current amount of hashrate available on the network, as well as, the number of nodes distributed across the world, it would take a lot of effort and money to make Bitcoin disappear. However, if Bitcoin never scales to expand itself to a greater number of users worldwide, then it would be doomed as other cryptocurrencies with better technology will take the lead.
Only time will tell us what will happen once Bitcoin fails to scale in the mainstream world.

I don't agree with the statement in red. I think that the transaction fees are decreased now because much
less people transact bitcoin than in Dec 2017 when the price reached its peaks. When the price increases to new peaks again in the future, I am sure that more people will want to transact (=sell their) bitcoin again and the network will be helplessly clogged again.
I agree, however, that if the bitcoin doesn't scale, it will be doomed eventually, even if it still can survive the next time like Dec 2017, it may be the last one it survives.