Like all the others.. one of many.. overabundance of supply = little demand.
Unless it has something else going for it, for example .com is just generally known and accepted, .de is the established tld for sites and companies in germany.. in this case it would have to mean one big site launches on a .healthcare and leads the way in becoming THE place online to shop for health plans, to the point where nearly everyone has heard of it.. but the odds of this happening are slim to none. Like the rest, its a great extension in theory but is likely to get lost in the mix of .everything else unless something brings it to the forefront and ingrains it. This can happen though and will happen occasionally, but is it enough to send everyone in field of healthcare racing to go register and launch on the .healthcare space instead?