Porting the client's C language circa 1996, not to mention sorting out all the server's reportedly homegrown scripting/DB interactions and probably C code to Unity or whatever (actually I think Unity is getting out of browser development)...I would
maybe only wish that job on my worst enemy, because it would pretty much go like
this.
Financially, it may have been feasible at UO's subscriber peak when the technology wasn't there. But browser technology evolves so quickly and haphazardly that much of the development would have just gone into dealing with clowns at Microsoft unilaterally reinventing browser standards. There's a reason why browser MMOs were a popular idea for like one year before studios started saying hell no.