Sort of. As we can see from this answer clerics and wizards are still more exponential than fighters and rogues, and end up distinctly better at level 20. However, the path to that point has drastically changed, and there are now levels where it is best to be a fighter! It's certainly still reasonable to talk about tiers of power, and the old tier definitions still make meaningful discriminations between classes, at a given level. What's different is that "tiers 1, 5, and 6 at this time don't exist" and that the 'flatter' power curve of 5e makes cross-tier play less awful.

Sort of. As we can see from this answer clerics and wizards are still more exponential than fighters and rogues, and end up distinctly better at level 20. However, the path to that point has drastically changed, and there are now levels where it is best to be a fighter! It's certainly still reasonable to talk about tiers of power, and the old tier definitions still make meaningful discriminations between classes, at a given level. What's different is that "tiers 1, 5, and 6 at this time don't exist" and that the 'flatter' power curve of 5e makes cross-tier play less awful.