Are many people really saying that now? I'm emphatically not an expert, but my impression was that it's generally agreed that there are clear theoretical signs (quantum physics vs. general relativity) as well as experimental ones (dark energy, dark matter etc.) that our understanding of fundamental physics remains highly incomplete, and that completing it will likely require a lot of very novel physics. There are some hot takes that there may simply be no grand theory that could explain all the relevant observations, but AFAICT they're far from being the general consensus. The more common pessimism is that humanity has been stuck in roughly the same place for several decades now, and there's no clear sign of any experimental or theoretical line of attack that (still) seems likely to get us out of it. This situation doesn't really resemble the complacent belief in the near-completeness of fundamental physics that supposedly existed in the 1890s. (And I'm not sure if that complacency was actually as strong as it's often claimed to be, at least among actual research physicists of the time as opposed to onlookers and popularisers.)