What I think is you're drawing false conclusions from the start with the same statistical fallacy that bits far too many people. You're looking at a chart by year, without the information of "out of how many" for each year.

Typescript may be climbing in SHARE of the market, but if the market grew larger even the ones you think went down -- PHP and C++ for example -- may in fact have gone UP.

it's like -- not to keep reposting this same comparison -- back in '08 when FF fanboys were heralding the death of IE because it dropped from 94% in '04 to 52% in '08. The problem with that assumption is that there were only 750 million Internet users in '04 and 1.5 million in '08... .so despite "losing" 42% market share they ended up gaining 80 million new users.

It is VERY easy to let graphs and charts sucker you into making false assumptions, especially when the pool size isn't revealed!

Thus the rest of your conclusions and analysis is on very shaky ground.