getting covid 19 isn't what should worry most people. the vulnerable high risk groups yes...worry about the virus itself. for everyone else, the threat is the very real possibility of hospitals being overwhelmed. look at China and how many of their doctors and nurses have been affected just from treating covid 19 patients...every doctor/nurse infected means one less available to treat those patients and others...for 2 weeks or more.
if enough get sick, and covid 19 patients continue to roll in to hospitals or other health care locations, people who might just get the sniffles from covid 19 may find that getting treatment for a broken arm, preventive surgery, biopsies for cancer and other such things may be delayed and could cause future/immediate complications.
the mass closures/postponements aren't about stopping the spread (far too late for that) they're about slowing it (and preventing a single area from being overwhelmed) so that healthcare as a whole doesn't collapse temporarily putting everyone at far greater risk for everything.
if covid 19 itself were that deadly for everyone, it would be time for everyone to lock themselves up in their homes for 3 weeks. but since its just about slowing the spread...just avoid super crowded indoor gatherings, and take normal anti-flu hygiene precautions seems to be good enough.
if anything does need to be handled radically different from the regular flu it would be to take extreme precautions when visiting the elderly or hospital patients (this is where you really need one of those n95+ masks)
for hawaii vacations, it likely means pearl harbor, museums, diamond head (to avoid possibly having to evac people from the trail), and perhaps hanauma bay may get shut down or have limits imposed on visitor admissions. conventions held in the convention center probably should be ordered closed by the state...but the chances that they'll do that are very slim...so contact the convention runners and be prepared for a possible literal last minute cancel.
as far as impacts to aulani itself...they may cancel/change their buffets to table service...or perhaps handle it like ohana at wdw (servers bring you food rather than you get it yourself). pools...I haven't seen anything about the virus being able to survive chlorinated water...but it seems like a fairly low possibility...still gotta worry about kids peeing in the pool tho.