At the time of cancellation, the A380F had exactly one order- a single aircraft for Emirates.

At what time? They had 27 orders from Emirates, FedEx, UPS and ILFC when Airbus decided to halt the freighter. Airbus stopped that version and converted orders or cancelled the existing orders.

Actually, there are more A380's on order than 747-8F

Currently there are 65 A380 orders awaiting delivery, to Emirates and Al Nippon.

There are 23 747-8F orders awaiting delivery to UPS. (no passenger 747-8 orders)

Given current production rates, they will be shutting down the 747-8 line before the A380 line...

Yep, 747 line will shut down after 50+ years and 1,500-plus built. A380 line will shut down in less than 20 years and fewer than 300 built.

I suppose, but the comparable aircraft, the 747-8i sold 47 units. (Another Boeing reaction to an Airbus aircraft) As far as development money well spent, the 747-8i was a huge loss.

Not that it matters much, in reality, both are done.

Notwithstanding what Wikipedia might say, nobody seriously expects another 65 A380s to be built in remaining two years before the line closes.

Do try to keep up - Airbus has ALREADY announced the A380 line will close in 2021, and most of those 65 orders you quote have been officially cancelled - outstanding orders for the A380 currently stand at about a dozen.

Considering the number of 747-8s I see in my wilderness area but on the flight path from Asia to the US prime air freight centers, is it likely the 747-8F will continue for a lengthy period at a relatively low rate. In other words is it likely the 747 will continue on well beyond the end of the A380 if only as a freighter? Aren't the advantages of the 747 over a 777 freighter significant for specific cargos? Not many can justify hiring the AN-225 but the 747 does seem to fill a niche unable to be filled by the 777. Certainly they won't go on like the C-47/DC-3 and 727-200 for which it appears nobody has a suitable replacement.

Without some 747 they could grow the 777 even more.

really, is that necessary? At least, when there are no orders, Airbus does the smart thing and cancels production. Cant say the same for Boeing. (one a month keeps a line open? until 2021?)

I dont mind Emirates reducing A380 orders when they add 70 other orders...all told, Emirates probably would have kept ordering.

The 747 was nice to fly, until the A380 came out.

Airbus does not have the numbers to get better fuel efficient engines ever.

Boeing is making money on each 747 produced, and will still be profitable even at one a month.

Airbus is losing money on each A380 produced (since last year), and will keep losing money until the line is shut down.

So who's smarter now, Boeing or Airbus? :}

Aren't both A and B at 0.5/month right now?

The 747-8F is at 0.5/month - not sure about the A380 (I seem to recall 2/3 per month but wouldn't put money on that).
At 0.5/month, the 747 isn't really a money maker, but it doesn't lose money either and it keeps the line open. Boeing still believes there is a solid market for the 747 Freighter - it's basically without competition in the over 100 ton freighter class and most of those 747F flying around today are getting seriously long in the tooth and will eventually need to be replaced. If they can get it back to 1/month (or higher) then the 747-8 becomes a solid money maker for Boeing.
As Sailvi notes, the 747-8 was a relatively inexpensive derivative of the 747-400 - Boeing didn't need to sell big numbers of the -8 to make money on it. I know what the business case numbers were for the 747-8 when it was launched. It's considered proprietary so I can't post them here, but suffice to say Boeing is easily on track to meet the business case assumptions.

Unless trans-Pacific trade flows slow down! But why would that happen?

At a 30% reduction in fuel they would still be more thirsty than the new twins (depending on units used) in the medium range. So at a 25-35% reduction you would still only be replacing existing frames and not growing the market.

I would expect that a conversion to a water bomber would face the same structural issues as being a freighter. It also is limited by airports that could handle it 130 worldwide.