Decreased number of Full Bitcoin Nodes can cause an problem or I am wrong

In my previous post I said something about Full Bitcoin Nodes. I will repeat that Full Bitcoin Nodes validates transactions in Bitcoin network. Because of that their role in a Bitcoin network is highly important.

Searching through public data I have found that number of Full Bitcoin Nodes varies from 2000 to presently 12163.

So, what hardware requirements one Full Bitcoin Node has to satisfy. As it is today 145 GB hard disk space with minimum write/read speed of 100MB/s, free 2GB RAM and Internet connection of 400 kbps. That mean you need good PC that has been connected on Internet. And that costs, right.

What is reason for those disk space requirements? All Full Bitcoin Nodes have blockchain database (that is the reason why technology is decentralised), that contains all previous transaction in the Bitcoin network. And when number of transactions increases day by day, that means this blockchain database will require more space and will be more robust.
Then we get to the point where Bitcoin blockchain network will require resources that someone need to pay. This at first was supported by standard bitcoin users and their resources, because those hardware requirements were low. But, it is obvious that hardware requirements for Full Bitcoin Nodes significantly increases, which shows that if there are no changes in Bitcoin network architecture there are two scenarios.

First one is significantly decreasing of Full Bitcoin Nodes number, or even Bitcoin network architecture to go toward centralised network with small number of Full Bitcoin Nodes (let say few). This option is almost not realistically practically sustainable.

Second one is that these expenses for maintenance of Bitcoin network will cover private companies or telecom operators that have benefit from keeping Bitcoin network alive. This means that private companies or telecom operators will invest and cover hardware requirements needed for sustainability of Bitcoin network.

Or I am wrong? Who knows.