Chinese diaspora is not really Chinese anymore. I'm more concerned about the opinion of the 1.4 billion Chinese.
to most of them, china is a foreign land. most have no connections at all and are mostly unable to speak the language based on my experience. in certain cases, they ditch their Chinese identity to assimilate into the local culture, some even go as far as to become self-haters in order to be accepted by their peers. I know a friend whose sibling turned out that way.
regarding the issues of language, it is very hard for these young diasporas to learn when they are being overwhelmed by non-chinese media 24/7. take Singapore as an example. the household might speak Chinese, but outside of it, in the schools, public, friend circles? most of the time it will be English or "Singlish". so at the end of the day no matter how hard the parents try there's a high chance the children will lose their ability to speak or even write as time go on, especially once they get out of JC/secondary school and they don't have to use it much. and then there's the case of fitting in and the want to be accepted by your peers.
I will give an example In my case. grew up in a Christian family, and went to a catholic primary school, then an extremely liberal and western leaning secondary education. was self-hating for the most part of my life until 2019 were I started to relearn the culture and language. now I'm getting branded as a traitor and "wumao". most of my friends circle I know all speak English despite being Chinese and they absolutely hate it when someone in our group tries to speak Chinese. once I tried to speak Chinese to this group and I got scolded for it. "this is Singapore, we are multi-racial, speak English".
to summarise it's the environment, if you aren't strong enough or have the will you are going to get swept away by the current.
so honestly, somewhat agree with this statement. I'm not saying all of us are like that, but most of the diasporas, might look Chinese, but in terms of culture and mindset they are anything but Chinese.
(of course, this is my own experience. some of you older guys might have different experiences)