Thing is, a competing product does not (at launch) have to match the entrenched one feature-for-feature. It just has to tick the MOST IMPORTANT boxes while being advantageous in other ways (such as being built on FAR newer tech, more reliable etc.)
Being built on newer tech isn't an advantage from a customer POV. It's only an advantage when the newer tech is better, and tbh I have a hard time believing that you'd match the performance and security of a mainframe that easily.
