Is it possible to bind dynamic texture samplers to a shader in DX12?
Yes it is possible by putting Samplers in descriptor tables to dynamically assign and index into them. Source: https://youtu.be/Wbnw87tYqVg?t=754

Here's an example that uses the HLSL root signature syntax to do this here:
https://youtu.be/Wbnw87tYqVg?t=5277