You're not wrong, an online games as service type model does seem more suitable for these titles than releasing a new $60 title every year.
However it would be a risk, can they make as much money from Fifa if they do this? Fifa 19 sold 20m as of February 2019. That's $1-1.2 Billion. Plus they already make money on microtransactions with ultimate team on top of that.
I'm not sure Fifa as one continuous product could come near that level of income in a year.