You must be thinking that if you upgrade to GA4 (Google Analytics 4), you will have to let go of GA3 (Universal Analytics). That’s not the case. At least for now.
GA4 and GA3 co-exist.
GA4 helps businesses better track their website traffic, detect trends, and see patterns in the customer journey.
Here are some of the benefits
Predictive Metrics for purchase progress including Revenue Prediction resulting in high-value audiences
Automated alerts of significant trends in your data like increased product demands due to a rise in new customers
Free connection to Google BigQuery for advanced analytics
All above available in the free version of GA4. Even if you choose to upgrade to GA360 (enterprise version) of GA4 the cost is significantly low as compared to previous versions of Google Analytics 360.
It is essentially a tool designed to understand and benefit from the online customer interactions on websites and mobile apps.