Long story short; The deadline already expired weeks ago, but Xinfin and AlphaEx still have the conversion mechanism in place and is still working as you read this. XDCE will be no more, and Xinfin will continue using XDC, which is not an ERC20 btw, so once converted, make sure not to withdraw to an ETH wallet, but an XDC one.

Short vid on how and where to click on once logged into AlphaEx:
https://www.youtube.com/watch?v=tyxcrc-c5KE
https://www.youtube.com/watch?v=Q8peu_5VKRI