Some of the good directions of MLIR like text format are already present in relay. And a natural next step would be the unification of relay and tensor level IR to bring a unified TVM IR.
Note that MLIR did not make the choice of IR design, so we still make a deliberate choice on how to design the IR. We could use more thoughts on “pattern-matching style pass” vs transformations on CFG(which we could move to a different thread). Note that both are pattern matching on different structures. In my experience, Halide’s loop nesting IR benefit from certain high-level information and quick prototyping. While CFG+SSA is good for codegen(role of LLVM).