The semi-good news for fire and Giant Sequoia groves is they'll probably do fine. As pointed out above, they'll receive extra protection though, where there's been extensive prescribed burns previously, as in Sequoia Kings and Yosemite, that's probably unnecessary. Although the Creek and other fires are incredibly intense and well outside the norms for any Sierra fire this century, Giant Sequoias have, historically (3,000 years) had such fires go through groves.
A recent study looked at the size of fires in two Sequoia Groves over 3,000 years. Fire intervals were between 2 to 15 years and were from 150 acres to 900 acres. Significantly, the periods of shorter intervals and larger fires occurred during warm and dry periods.
The study said:
Sequoias can sustain very high fire frequencies, and historically they have done so during warm, dry times. We suggest that preparation
of sequoia groves for anticipated warming may call for increasing the rate of prescribed burning in most parts of the Giant Forest.
That said, there's a number of groves -- the majority -- that haven't had prescribed or wild fire move through them and do have huge amounts of fuel (deadfall and dense forest) that otherwise wouldn't be there were fire a normal part of the forest ecology. There could be some mortality even among the older trees (> 500 years).
As for drought, the study above pointed out GS survived the Medieval Warm. Two droughts of over 1,000 years from about 900 -- off and on -- to 1100. These droughts were enough to have completely dried up Tenaya Lake and other Sierra streams and lakes. So, again, there's hope based on historical data.
The bug killed tree case cited in the article seems to make a generalization of a single tree to all Sequoias. Nate Stephenson, quoted, does say it's worrisome and no question he's the expert on GS. Without more evidence, as he says, I'd not panic just yet. Also, it's arguable that because of the unnatural density of all the other species of surrounding trees (white fir and other conifers) that wouldn't otherwise be there were fire a part of the regime, the ground water is being sucked out at a much greater rate than otherwise, weakening even GS and making them susceptible to bugs.