Large power transformers have efficiencies in the 98-99.75% range.
I don't doubt switch mode could be smaller and cheaper up to some size, but I am struggling to see transformers larger than about 5 mva being replaced with power electronics.
Solar farms etc have inverters in modules I believe 500 kva each - and of course the power electronics are necessary there, there is no substitute.
I have a 20 MVA transformer that is nearly at end of life and would be open to cheaper replacements.