People will go also crazy buying Crypto after they buy coinbase shares,
I doubt it. Coinbase is just another company among thousands that are selling shares on stock market. Companies with more stable situation and a longer history that stock market investors prefer over a company they have never heard of working with something (bitcoin) they also may not even have heard of or worse heard and believed some FUD about it!
Coinbase going public is a major milestone for bitcoin. It is the first major crypto-related company to truly go public. Holding a share of coinbase is not he same as holding bitcoin, however it is a metric as to the market's confidence in bitcoin's long term success.
and with a valuation of 68 billlion for coinbase, BNB will skyrocket in April.
You are confusing Coinbase with Binance.
BNB is a centralized shitcoin created by Binance and is pumped and dumped by them which has nothing to do with Coinbase.
BNB is a centralized token-coin created by Binance, not by coinbase. BNB provides utility to binance customers by allowing them to pay lower fees while using the binance exchange. I would not say that BNB is as worthless, nor pointless as the majority of altcoins out there.