Yes, let us replace all the old technology.
We'll get the expense whch can be written off (it has been an industry maxim since forever that IT departments are a money sink and a Tax Loss). Shareholders=happy.
We'll be able to employ lots of programmers. Jobs=popular.
We'll experience cost overruns in the millions. Vendors=ecstatic.
We'll miss deadline after deadline. CoB="Concerned".
We'll probably experience several false starts as we discover the hard way what we forget to spell out in the spec or what the Universities forgot to teach *this* crop of IT Graduates. CoB=fired (problem solved, at cost of "New Broom" policies that invalidate man years of work - and before you scream and leap, what woman would be stupid enough to get ensnared in this can of worms?)
I can see no downside to the plan.
On the other hand, we *could* just develop a migration path to a more cross-connectible solution over time. in which new development was built using newer ideas.
Yes, I *know* we all said "yes" when given those "are you planning to migrate from mainframe to client-server architecture in the next five years" questionnaires at every f---ing IT confab run in the 90s, but we did that to qualify for the free tote bag of goodies.
No-one in their right mind would seriously jeopardise their career by actually *doing* that. The vultures would start circling as soon as you ran the first project meeting and from that moment on your days would be numbered as every pair of eyeballs in the place would be vetting your every move just waiting for the main chance to crap all over you and take your job.
Rewrite everything in "C"? Are you barking mad? In what world does *that* make sense? All the expense of rewriting your financial software, but in a language intended for crafting device drivers. Remind me what your degree subject was.
Change is bad. Ask the guy who was put in charge of the Y2K project so his failures would be public enough to fire him should he continue to agitate with the board for unpopular tech reforms.