even when attacked from the inside by blockstream/core it just forks and offers two chains. at least one will continue delivering p2p electronic money to the people with low fees. maybe both? we'll see. 
People leave bitcoincash because their block is still not perfect, so they prefer to go back to bitcoincore. And I'm sure bitcoin will reach $ 4000 by the end of this year 
I think they did not leave bitcoin cash because of their blocks not being perfect. I think it is more like they use Bitcoin Cash so they can earn more bitcoin.
I think this is also the reason bitcoin' s price is making another good leap. I wonder how long will the price go like that, we all know that bitcoin will be experiencing another issue which is the debate on November.
Actually you are right, bitcoin is unstoppable because everyday, month or year bitcoin rise up until everyone knows what it is. Bitcoin become popular every single day past and because of that the currency make it high also to attract every one to use bitcoin. I think bitcoin is the start of success of every person who use it and also the beginning of micro money in every country. Because the believer of bitcoin no one can stop bitcoin.