No. At this point in time Thunderbolt is basically USB4 ( or USB4v2 in TBv5 case). USB4 leaves a bunch of useful stuff 'optional'. Primarily Thunderbolt makes a larger subset of the USB4 standard mandatory. Plus it pragmatically mandates that you don't 'cut corners' when implementing USB4.
All of this 'extra mandatory' stuff gets certified by Intel and then get to put a "Thunderbolt" label on. More than a few vendors are just going to slap USB4v2 on their implementation and just ship it ( skipping the official TB certification. That is cheaper).
TBv5 also pulls folks toward correctly implementing DisplayPort v2.1.
[ Even Thunderbolt v1-3 were not compatible with FireWire either; before the 'merge' with USB. ]
What? You can go from firewire to thunderbolt (2?) then to thunderbolt 3...
Video here