Like is Out, Yeah is In.

 'Like' on the way out. 'Like: __' was often used, for example, as a device of indirect quotation, where the quoted material is first-person, and one acts out the speech expressing what one thought or felt on the occasion. "Like: 'What is this guy doing?'"; "Like: 'I was all woo-woo", you know?'. 

At around the same time, 'Yeah!' has come in, or rather has come to play a new role. In this usage, it is not a response to the interlocutor's statement or question, but occurs within one's overall speech, mostly but not entirely as a space-filler, between sentences. It is used among other things to announce a change of topic, or just to sustain a positive vibe while keeping the floor -- to decide either on the next topic, or to keep on with the present one. Often it signals that the next utterance will sum up the previous ones. 

While I'm at it, the use of the term 'obviously' -- in this role it has been around a while -- is interesting. I hear it as: 'What I'm about to say perhaps goes without saying, but nevertheless I say it just to be absolutely sure there is no misunderstanding, and it's worth saying for the sake of what I'm going to say after.'  

Invertebrate and Inveterate, Incredible and Incredulous

My diagnosis of (one aspect of) changes in language runs as follows. A relatively common word is in use (say 'outrageous', 'uninterested', or 'deny') and another relatively rare word that expresses a different, typically more complicated meaning, which often sounds similar to the first one (say 'egregious',  'disinterested', or 'refute'). Perhaps imagining a certain show of erudition, people begin to use the latter word for the former, not being aware that the latter does not mean the former. But then, if the virus spreads sufficiently, it does means the former. So to speak. (I've discussed those particular examples previously; the links are on the upper right). 

So two newish examples. The first fits the pattern to a T. I've heard it before, but here is a recent, public example from the teevee. Victoria MacDonald of Channel Four News used 'incredulous' for 'incredible' (or 'really incredible!').  But of course -- assuming the old meaning -- strictly speaking, that is ungrammatical nonsense:  You can say x finds y incredible, but not that x finds y incredulous. What does make sense is that x is incredulous at y. The incredible thing vs. the incredulous person (the agent and patient roles are reversed).  The second doesn't fit the pattern, but fits it as it were in reverse.  Twice now I have heard 'invertebrate' being used where surely what was meant was 'inveterate'. Now all people know the word 'invertebrate', and very few know the word 'inveterate'. My diagnosis is that person is vaguely aware that there is such word, but can't quite recall it. If anything 'inveterate' connotes strength where 'invertebrate' connotes lassitude, but there it is.