In a statement made to The Verge, an Apple spokesperson was quoted as saying, “Over a decade ago, Apple partnered with Intel to design and develop Thunderbolt, and today our customers enjoy the speed and flexibility it brings to every Mac. We remain committed to the future of Thunderbolt and will support it in Macs with Apple silicon.”
As to why some were worried about this, it is because Thunderbolt has yet to be seen or offered on any of Apple’s non-Intel based products. Even the iPad Pro uses USB-C and not Thunderbolt 3, while the ARM-based Developer Transition Kit also comes with USB-C ports and not Thunderbolt 3 ports.
However, the good news is that based on this statement, it seems that Thunderbolt will continue to be supported even on ARM-based Mac computers, which is good news for those who rely on the port to connect devices or to make huge file transfers.