It might, but will be 10.15+ only. RX 5700, RX 5700 XT, and RX 5700 Anniversary Edition are all currently supported in macOS Catalina 10.15.1+ for eGPU (not in 10.15.0/initial release).
Keep an eye on this for Apple's official updates:
Learn how to access additional graphics performance by connecting to an external graphics processor.
support.apple.com
Sonnet says only WX7100, WX8200, WX9100 are macOS compatible at this time. WX5100 is Windows only. RX5500 is still not OFFICIALLY compatible for eGPU (yet) and Sonnet says for Windows only.
The W5700 might be a popular "pro" GPU given the relatively low price for what it's offering. Have seen some initial articles that say the RX 5700 XT
might be a better choice. I'm sure people will start testing it very soon after initial availability.