I don’t think there’s any need to upgrade now if it’s serving you well. At the very least, you should be good for security updates for another two years.

There are still plenty of advantages to upgrading, of course. Even if you don’t need the extra processing power, the longer battery life could be quite useful.

(And we’re not talking small differences here … modern MacBook Airs offer like 5x the processing power and 3x the battery life.)

2020 should receive OS upgrades for another 3 years.

Also apple has never made an i3 air. There was an m3 MacBook which was older, I believe support for these has now ended.