They already tried that with TamTam (https://tamtam.chat/) which is also owned by Mail.ru Group. I don't know anyone who uses it though and ICQ had a huge userbase in early 2000's in Russia, so maybe that's the reason?
None of us used official client. Only reason it was popular is because protocol was reverse engineered and there were clients for everyone. This is just capitalizing on ICQ name that many of russians feel nostalgic about.
I still remember my 7 digit invisible vanity number.
I still remember my 7 digit invisible vanity number.