Of course they're matching the IP68, SD, etc. -- all phones are. IP68 used to be a called a "Gimmick" by tons of Samsung users .. Now it is a standard. That is how things work. People get new things and at first don't like them then it becomes standard across the board so no surprise other manufactures are doing it.
I believe the G6 will be good on sales but I wouldn't expect it to be at Samsung levels .. TBH I don't think anyone would think that. I think everyone would expect the Samsung to beat pretty much any other Android phone in sales since it is most known by consumer (hence Samsung spending 10 Billion last year on advertising).
LG just put out a good phone to compete. For me the S8 really didn't have much.. Bigger screen / battery but it is pretty much an S7 Edge (but bigger). Oh and a faster SOC but I doubt anyone on day to day use is truly going to notice. That is why Android is nice though
.. everyone can get what they want. Some love the Samsung apps.. I don't since I use all of the Google ones that do what Samsung ones do (since they're dupes of the Google ones usually) and will work on any phone (so I am not locked into Samsung).