Most times anyhow.
There have been instances of units being removed from a codex, but it sounds like the ones you have are core units (which i don't see goiing away) Lords are THE necron
hq (ignoring Ctan for now) and will always be, warriors are the basic (and currently only) troops choice, so no chance of them vanishing, and Destroyers are the iconic Necron Fast Attack, and nice plastic models to boot. They're likely staying.
Frankly, the necrons are way low on choices comapred to modern dexes, so they'd be far more likely to be adding stuff than removing it
New rules, same models, likely new extra models too.