Nearly all usecases for a power transformer are now better served by a switched mode power supply.
They tend to be much smaller, lighter, more efficient, cooler and cheaper. They also have features like adjustable output voltage, current limits, and overheat protection. Some can input and output AC or DC, at a configurable frequency and sometimes waveform. Some offer the same galvanic isolation that a transformer offers too.
The core of a switched mode supply usually is a transformer, or at least an inductor, but the key difference is that it operates at far higher frequencies than classic uses of transformers, which allows them to be far far smaller, and therefore cheaper for the same power output.
Are you saying large Transformers 1 mva, 10 mva, 100 mva, 500 mva are obsolete and should be replaced by switched mode power supplies? What mva is the threshold?
Eventually it will be worth switching out old transformers - they contain a massive amount of valuable copper and quite valuable steel, and their lower efficiency means every year they remain in service they are wasting $$$'s of electricity.
Transformers in cities can often be replaced with much smaller switched mode units underground, allowing the building housing the old transformer to be rebuilt as luxury flats to make the project much more profitable too!
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.