Like the OP I have 4 grandkids (little) whom I would like to help some day if I can. We should be fine in retirement financially, but will not be so wealtlhy that our ability to do this is assured 14 years from now under any circumstance.
After considering the alternatives, my DW and I decided that the best course of action would be to tend to our own retirement needs, maxing out our tax sheltered alternatives, and saving hard. 95% of our savings for retirement are tax-deferred, not counting the house. If all goes well, the money will have grown tax-deferred and we will gift it to them as we can.
OTOH, should unexpected needs arise involving long term care, an unprecedented stock market skid, a wayward grandkid or two, etc. those funds would be available to us for our personal needs (and our kids would not be burdened), rather than being tied up in a 529. True the college funds would not longer be feasible in that unlikely scenario, but we feel it is best to gift that money if and when it truly clearly and permanently unneeded by us.
Hopefully we will do well, will gift the money, and everyone including my kids will benefit from any excess we are able to generate. But I'd rather not gift money I am not sure I won't need some day.