Wouldn't it make sense to nerf the later, greater sources of gold, but not basic empire-building ones like trade routes?
What later, greater sources of gold are you talking about?
I agree, but am not too strongly opposed to the Trade Route nerf because gold balance is much better now in the current beta!
Yes, the balance is much, much better! Especially with the RA prices, which I think are great right about now (i.e., I'm consistently finding that a tough call how to spend my money! Unless I have an alliance with the tech runaway, but that's another story).
@wobuffet
Trade routes are a national form of

-per-

pop
That's true, but trade routes do weigh the Capital vs Satellites differently, which could be interesting (even though I don't like exacerbating the crazy levels of Capital-loading already necessary for tall games).
At least one or two of the Gold buildings could definitely use some changes for flavor (i.e., not three buildings that do literally[!] the same thing: "+1

, +25%

in this City"). For example, something like
Market: +2

, +10%

, +1

on Luxury resources worked by this City, 2 Merchant slots
National Treasury: (
requires Market in 75% of Cities) +15%

and 1 Merchant slot in this City, +25%

Gold from Trade Routes empirewide
Bank: (
no prereqs) +10%

, +1

per 3

Citizens, 1 Merchant slot
Stock Exchange: (
no prereqs) +1

, +25%

, no Merchant slots
could make Gold building decisions much more exciting and situationally interesting. (Heck, I'd probably go all the way and change a couple of the Science, Cultural buildings as well – most of them are pretty bland. Gold buildings, though, are by far the worst offender.)
Oh, and by the way, shouldn't the hammer cost of Machu Picchu be reduced (or the TR income +% increased) in light of the v131.1 Trade Route nerf?