Zelenskyy: At oh eight hundred hours, Kyiv time, the Romulan Empire formally declared war against Russia. Their cloaking technology is already being integrated into our drones. So I lied, I cheated, I bribed men to cover the crimes of other men. I am an accessory to murder. But most damning thing of all, I think I can live with it. And if I had to do it all over again, I would. The CIA was right about one thing. A guilty conscience is a small price to pay for the safety of Ukraine, so I will learn to live with it. Because I can live with it. I can live with it. Computer, erase that entire personal log.
To be vaguely credible for a moment, it is and it isn't. On the one hand, Russia will have a very hard time replacing high end losses like Su-57s, Ka-52s and other hardware that relies heavily on modern electronics, materials, and manufacturing techniques. On the other hand, they don't need any of those things to grind Ukraine down by sheer weight of numbers, armour, and artillery fire. The Ukraine conflict has basically devolved into WW1 trench warfare, which suits Russia prefectly. A slow, grinding, attritional war is one that plays entirely to their strengths. It doesn't take a lot of modern to equipment to lay minefields and pre-range howitzers, so on the defence Russia can crush any Ukrainian push, and on the offence they can pay in blood for every mile.
Ultimately, the loss of something like a Su-57 is largely meaningless to Russia, because they only ever existed as a propaganda tool in the first place. Even if the Su-57 was the ultramodern fighter Russia claims (its not), they only ever built six of the damn things. That's a rounding error compared to the US stock of F-35s and F-22s. It's no different than all the noise over deploying the Armata. Whether they did or didn't was never going to matter because they've got something like twenty of the things in total, and that's not enough to affect anything in a conflict of this scale. It's all just propaganda and posturing.