The ETH has been under pressure for a long-time. The biggest problem is that the more data we have (especially when we can see the geographical and temporal variations) the less easy it is to fit to the idea that space travellers are dropping by in their fancy flying saucers (how we look back to the simplicity of the early, Contactee era with a misty eye). We also have reports of contacts with "aliens" going back centuries (along with other "ascended" masters) and beyond that a range of other entities, suggesting the real possibility that these aliens are just new masks worn by an age-old phenomena.
Readers who've followed this blog since '06 might recall my own disillusionment with the Extraterrestrial Hypothesis.
[Follow me on Twitter.]