The main indicator that a language isn't dying out is that it's able to change and adapt (as you also said). With my mother tongue, Estonian, we have the same problems – youngsters using very phonetic or just heavily abbreviated words, which annoys me as well. However, in Estonia, I feel that people are very proud of their language and whenever someone tries to "break" it, they will probably get a stern talking-to.
TL;DR: I believe it is, as you said, a natural phase in languages. This is the exact reason why we have rules – sure, sometimes you might forget about the rules, but they still exist and if you want to achieve something in life, you have to remember the rules.