Then if at current specs we're not able to keep up 100k nodes, why do you think it would be possible with an x100 chain?
Now there are approximately 10 million users and 50 thousand full-nodes. Only 0.5% of the total number of users hold a node. Despite the fact that the cost of the node is minimal. And it's not going to improve.
Let's increase the block 10 times. Expenses will increase, but not by much. To keep a node with a 10MB block, it is enough to have a 2TB hdd for 5 years. You can take the price of such a hdd and divide it by 60 months. This will be at the level of how much users are currently paying per transaction, for each transaction. But in the end, we can get a 10-fold increase in the number of transactions and about the same increase in the number of users. Even if the percentage of users holding a node decreases, for example, to 0.1%, then in total we can get 100 thousand full- nodes. Even if the number doesn't increase, we don't lose anything. Even if it decreases slightly, which is extremely unlikely, the advantages that we will get far exceed this minus. The probability that the number of full nodes will decrease to a critical level is 0.
But this is moving forward, instead of the ass where Bitcoin is now.
The problem with these fees right now is mainly caused by slower blocks, hash rate is dropping, there will be a retarget, the capacity will go up by 20%, everything will be fine, this would have happened with smaller blocks or bigger blocks.
The main reason for this is small blocks. If there were large blocks, users would not even notice the hashrate drop.