how to raise our kids?
Give them as much room as possible to let them grow into independent and strong people. Make sure that all they need to succeed in this is available to them.
how to ensure that they will not abandon us in the future?
Don't do that! It's their choice to abandon or not to abandon. If their environment of upbringing has showed this to be a part of society as a whole they maybe will consider not to abandon us.
do we even believe that tradition of kids taking care of their parents will still exist in the next 20-30 years?
We see these traditions erode right now already. Many families have to generate at least two incomes to keep everything economically a float. Taking care of the elders is tough with both parents working. In my estimation the future in this doesn't look all peachy and nice. I believe we'll have less multi generation families under one roof and more placing of elders in nursing homes or with dedicated payed help in their homes. One factor might also be service robots that will be used to reduce such costs further.