I have actually successfully integrated an adult high prey drive dog with an adult cat (with the cat being a newcomer), so I know it can be done, but it takes a lot of work, a lot of time and a very special set of compatible animals. I also have a fair bit of training background and I still wouldn't have done it if my daughter's first word hadn't been "kitty," her every Christmas and birthday wish hadn't been "kitty" (in a house full of dogs), if my dogs had been different than what I had at the time and there hadn't been a kitty who desperately needed a home. I'm not so sure I would attempt it with this particular dog (2yo, untrained, extremely fixated on cats) without professional help because the consequences if things go wrong can be heartbreaking.
By the time our cat came into our family, my high prey drive dog, despite being a non-traditional obedience-bred dog (British bulldog, of all things) had had years of practically daily training (because we both really enjoy it) and already sported a number of titles in obedience, agility and even trick training. He might look for all the world like an overstuffed, drooly, snorty couch cushion but don't underestimate him, he's not your standard family pet. He's going to be 9 this year and we still work several times a week, just for fun. Important here is that despite his high prey drive, he has a reliable recall off-leash, heels well and, when in doubt, looks at me for guidance. I also did a lot of work desensitizing him towards cats and other small furry animals outside our house and was able to reliably have him heel off leash past the barn cats before we even considered bringing a cat into our home.
Even then, when the cat (who was excellent with dogs) came, after weeks of careful supervised successful interactions, I got overconfident and one moment of inattention led to a serious chase. Thankfully the bulldog immediately stopped when I called him, but it was unnerving. After that, I decided that the stress of being constantly vigilant was too much so we kept the cat free roaming upstairs, sleeping with my daughter and the dog downstairs, sleeping in my bedroom like he always had. They didn't see each other for the better part of 6 months. The cat slowly introduced himself - when he was ready, he'd come and sit on the balcony where the dog could see him but not approach and the cat could see us, spending weeks just sleeping there all day long while we went about our business on the main floor. For weeks, the cat would inch closer and I'd reward the dog for not paying any attention.
All and all, it was almost 9 months from when the cat came home to the day he casually hopped the babygate and said "here I am, now feed me." I'm not going to lie, I was in a blind panic when he did that but the dog made a show of ignoring the cat and then wanting a cookie so all that training had worked. It was another three months or so until they both started sleeping on my bed together.
My dog is now reliably good with cats that I bring home as long as they're introduced properly (slowly, over time). Outside, he will still chase anything small and furry that runs if he gets a chance and isn't explicitly told not to.
If you do decide to go for it, go SLOWLY, carefully, take much more time than you think you need and have a plan for what you'll do if it doesn't work.