In my program, we had a saying that lowbrow philosophers end every argument with "Plato said it first"; middlebrows say "Kant said it first"; highbrows say "Wittgenstein said it first."
Modern philosophy hasn't "obviated" Plato, per se, but any competent philosopher today can discuss what Plato thought generally and how/why we think differently today. The philosophical method of analysis and argument remains, but no one talks seriously about Platonic forms except as part of the history.
It seems to me quite a tall order to say that "any competent philosopher today can discuss what Plato thought generally and how/why we think differently today."
When I say "any competent philosopher", I'm being specific to the Western philosophical tradition. Up through the 19th century, any education in philosophy, classics, or the humanities was virtually certain to include reading Plato; since then, more organized philosophy degrees in university always have some ancient philosophy requirement that includes Plato/Aristotle. Additionally, Plato is frequently used as introductory material in philosophy classes to demonstrate how it works via the Socratic method. Within the confines of "professional" philosophy today, it's almost impossible not to have a basic grasp of Plato.
As for how and why we think differently today: any study of the history of philosophy is partly the study of refuting earlier philosophers. If you're aware of Plato, you're aware of criticisms of Plato and how that formed the basis of other ideas.
Intuitionism/constructivism has gained much momentum in recent years.
It is the foundation for Hawking’s model-dependent realism [1]; or more radically Dummett’s anti-realism [2].
Speaking purely about Mathematics - there have been great strides in constructive mathematics in the last 3-4 decades, and great overlaps with computer science (Curry-Howard-Lambek correspondence). A formalist might even say that the fields of logic, mathematics and computer science are identical.
Modern philosophy hasn't "obviated" Plato, per se, but any competent philosopher today can discuss what Plato thought generally and how/why we think differently today. The philosophical method of analysis and argument remains, but no one talks seriously about Platonic forms except as part of the history.