What do you think? Will "De-Fi" beat banks in the long term? Or is it still too early to tell? Do banks consider "De-Fi" as a threat to their existence? Your input will be greatly appreciated. Thanks in advance. 
No even we count for decades. The banking system is so huge and will evolve more while in progress. Big individuals, business owners, big people, downed to a regular person will still prefer a centralized system because of safety, assurance, and being insured in case of a fu*ked up.
But honestly, I want to see a full decentralized system but already accept the reality that it won't happen even by less chance.
Rather than replacing banks, why not hope that they will exist at the same time, take advantage of them and enjoy both.
i also don't think that we will see this happen in our lifetime. the traditional banking system has been established for decades and decades and replacing them with the new technology is very far from happening, as of this moment. even now, DeFi system is showing vulnerability to outside attacks. so it is quite difficult to sell the DeFi system to ordinary users. maybe, right now, some are enjoying the benefits of DeFi but the security alone, it can't guarantee its users. just be grateful that people can enjoy the DeFi market along with the traditional system. so it is their choice how they can grow their funds via these options.