I find it is a fading tradition more stronger in the smaller cities though. One of the behind doors discussion that my wife had with her parents was "he will take you back to his home country how will you be able to look after us". But I have joked with her we should start a nursing home business here which I dont think exists and could be a start of the next boom business here. 

Actually saw a Old People's Home here today on my way to work. Run down crappy place. No surprize there.

The responsibility of children to take care of their parents here in China is not a tradition, it is definitively a Law to the effect, and it is my belief that it is also mention in their Constitution.

As an example, my GF gives her 83 years old mother, who never worked so she has no retirement income, 900 Rmb every month out of her paycheck.  I most also say that her mama reciprocates by doing all household chores like cleaning, cooking, washing clothes, etc while my GF works and her daughter goes to school. 

I do not think the practice is fading at all.  If an elderly was to complain that the son or daughter refuses to take care of them, it could be punishable under the existing Law, and quite a loss of face among friends and neighbors.

my parents still expect me to take care of them when they get old....and i am willing to do this.

1st,  i came from my parents(although ppl say human came from god, but without my parents, then without me), they took care of me when i was young, so it is my duty to take care of them when they are old,in my opinion, it is reasonable.

2nd. i am the only child in my family like most of the city kids. when they are old, if i i don't take care, who will take care ? send them to seniors' home ? my parents could go there if they want to, but if i raise this topic to send them to there, ppl in my hometown or my friends will definitely laugh at me and piss on me.

3rd, taking care is not all related to finance, i think the old ppl want more mental care as we Chinese are more traditional,the old will feel gratified if being cared.

4th,  when the expats dating Chinese,they know they are dating Chinese,right? so they should accept the culture,otherwise,why date ? the same, the Chinese who date with foreigners also need to accept the different cultures, the Chinese and foreign culture merged together and have combination. then can have a good future.

Its both a tradition and a law, more a tradition than the latter.  That being said if the son/daughter doesn't provide financial support for the elderly parent, the parent can take their son/daughter to court.  

But like i say this was a tradition first, then a law.  it dates back to the Zhou dynasty and was a central idea put forward by Mengzi.  I will bet anything it wasn't punishable by law in those days but it is now apparently. not sure how often it goes to court though, it would be really embarrassing for both parties.

And its not a fading tradition, if anything its becoming a hotter topic of conversation in modern china with all the migrant workers and one child policy.