As just a general thought, I think the negativity has far out of proportion. While I agree with the disappointment with regards to the thinning of the collection and the loss of the aviaries on the other side of the canal, I don't think equating London to Bristol is in any way a logical step from this, not least since the two societies are nothing alike and the sites on which they operate are completely different. London Zoo is within a Royal Park - ZSL do not own the land in any way, and housing (at least not in the way people are envisaging) cannot be constructed there.
London isn't flagging financially. ZSL actually had a net profit across 2020-21 of 1.3 million, despite that year being the toughest for zoos around the globe ever in terms of the obstacles they had to overcome. The situation is not in any way similar to that in which Bristol found itself having to close earlier this year, other than that there is a 'back-up' collection in the outskirts.
For the management, there is no problem. They were profitable in 20-21 coming off a net deficit in 19-20, especially impressive given they lost out on over 700,000 visitors due to the virus. In fact had the zoo been open throughout, attendance would likely have been around 1.3 million, a record. From a business point of view, the zoo has been nothing but successful over the past year or so given the situation at hand. From a research point of view, the zoo has been nothing but successful. From a conservation point of view, the zoo has been nothing but successful. There is absolutely nothing indicating the zoo is flagging financially or in terms of conservation output, so the comparisons to Bristol are entirely unfounded.
With regards to the post quoted above, what you say is objectively wrong. Whipsnade receives very, very few visits from tourists. Almost nil. And I'd be very inclined to say that, despite having no figures to back me up, the majority of visitors to London Zoo do not live in London. The zoos are polar opposites in terms of where the visitors come from (NB: this is not the case in Bristol, where neither the zoo nor WP get many foreign visitors). So claiming that visitors would not bat an eyelid is just not true. Whipsnade is hellish to get to by public transport - even were the zoo to close (not an eventuality there is any reason in considering anyway) Whipsnade's visitation would hardly increase, and the input of money from tourism into ZSL would all but vanish.
As for your question on whether people see London Zoo still existing in 50 years' time: absolutely. If you think London is struggling financially, read their statements - they tell the opposite story. A decrease in collection size possibly correlates vaguely with financial troubles generally speaking, but that isn't the case here.
Just to be clear, I don't like the direction London is going in. I think there is masses of wasted space and that management have made poor decisions in the past. But that doesn't mean they're struggling. And people saying they're going to close because the owl aviaries are no longer there are getting vastly carried away.
I completely agree.