This article not only introduces Comet Lake U for the MacBook Pro, but also suggests that Amber Lake Y for the 2018 MacBook would get USB 3.1 Gen 2 10 Mbps.
https://pc.watch.impress.co.jp/docs/column/ubiq/1126720.html
If true, that means it could conceivably also get Thunderbolt 3.
https://pc.watch.impress.co.jp/docs/column/ubiq/1126720.html
If true, that means it could conceivably also get Thunderbolt 3.