It is possible, but absurd. Why more layers if layer 1 works fine just increasing the maximum block size? Bitcoin Cash did it and works flawlessly. Just try it.
> Bitcoin cash pays the price through centralisation
What centralization? If you are referring to the node implementations, it has several [0]: Bitcoin Node, Bitcoin Unlimited, Bitcoin Verde,... Bitcoin BTC has basically one: Bitcoin Core [1]. If you mean mining, it's the same as BTC, same mining algorithm, same miners.
> It can still only manage 100 transactions/second
True for now, but it's way more than it needs right now now [2]. But don't worry, this month upgrades to ABLA [3], and will be able to scale to as many tx/s as needed.
The increased block size increases the amount of storage required to run a full node (and also the bandwidth required to sync nodes). Even at just 100 tx/sec, you need 14x the storage of a bitcoin node (so around 10TB vs 700GB for bitcoin). That puts it out of reach for many people to run and so making it more centralised.
To compete with a payment rails like Visa and Mastercard, you'd need to increase that to 10000+ tx/sec, making running a node complete unfeasible for most people to run.
There's simply no such thing as a decentralised blockchain network with unlimited block-size. At some point if you want to remain decentralised, you have to create layer 2+ networks that can handle the smaller, high-bandwidth transactions, and so you may as well commit to that model now and focus on making the base layer as robust as possible.
Ultimately for a money to attract the most value, it needs to optimise for the very largest transactions, and offer the most robustness (i.e. most decentralisation). This is precisely what bitcoin has done.