Would a fun, non-solemn Bond movie --

Why not make 2. One a depressing film with DC with a 2.5 hour running time and the other a fun one with one (or 2) dimensional characters. The fun one would have a much shorter running time and smaller budget. The fun one may make more.

"Time is an illusion, lunch time doubly so" - Ford Prefect

Yes, it totally would. Right now the trend is in favor of meta/fan service. That's actually why Spectre has some "gadget"/goofier moments like with the car. Like superhero movies now try way harder to perfectly recreate look of the comics, unlike the early 2000's where it was always a "loose" interpretation (e.g. X-Men)

Yes

Yes a fun, non-solemn Bond film such as Goldfinger could make a lot of money today. For example 'Kingsman: The Secret Service' proved that a Sean Connery/Roger Moore type Bond film could be a critical and a financial success today. So yeah that kind of Bond film will still make a lot of money today.

Goldfinger was good. I think the early Connery Bond movies had just the right tone.
Things got too silly in the Roger Moore days.

As far as fun, non-solemn spy movies in general, check out "The Man From UNCLE." Audience reactions to that might give some indication as to how a Bond movie with that kind of tone would go over today.

Of course it would! People love well-done action movies with funny touches, the secret of Marvel's success is that they've revamped that old formula, added CGI, and did it right.

There's no reason the Bond franchise can't do the same... once Craig retires. Comedy isn't his strength, to put it politely.