a) it goes Mach 1.6, and b) it's virtually impossible to detect via RADR. If both a) and b) are true it's impossible to take out with missiles (which require a target of some sort before you can fire them)
Two things. First, Mach 1.6 is not that fast relative to the speed of air-to-air missiles. Sidewinders (from 1956) travel at Mach 2.5, modern AAMs exceed Mach 4. Second, RADAR is not the only way of targeting missiles. Modern anti-aircraft weapons use a combination of RADAR, IR, and acoustic targeting. The kinds of jet engines that can get you to Mach 1.6 basically paint an enormous IR arrow in the sky with the tip at your aircraft. This was old tech a decade ago.
This will, in theory, make every other combat aircraft anyone has ever designed obsolete.
No, they're going to be made obsolete by cheap semi-autonomous drones that can be launched en mass from aircraft carriers and can handle 20G turns for evasion, which gives them a massive advantage against missiles, which have very limited turning abilities.