I firmly believe the number 1 reason behind the perceived failure or lack of success of the Amazing Spiderman franchise is the oversaturation of Spiderman.
First there have been several Spiderman related TV shows but the main issue is all of the movies. 5 SPIDERMAN MOVIES in 15 years. That's alot. Batman has had 8 in 45 years. Combine that with how similar the story of the first Spiderman was to the story of The Amazing Spiderman, and you get a public that's sort of over it. The public being over it, i believe combined with just not very good story telling in the 2nd Amazing Spiderman movie has put Sony in a rough place. Marvel can make money from Comics, special additions, an Avengers or other cross over, and toys from a movie and because it's Marvel they don't have to advertise as much. TASM2 barely broke even. Sony has discussed for years their willingness to try to get "Spiderman" into a marvel film, i think with the current financial situation they might be willing to either share rights and profits or sell a % of the rights back to Marvel. if this happens here are some things I think could allow Marvel to artfully introduce Spiderman into the MCU and give him his rightful place in the marvel universe.
1. Don't recast: I am not in love with Garfields portrayal. In a way i think he's too "this generation" He's very cocky but not deserved, not really creatively funny just funny in a "I'm cooler than you and I'm not nice" kind of way, and he is also very whiny and self involved. That said it's not Garfield as much as it's the writing. The whole "Love story" in the Amazing Spiderman, where he never said more than 2 words to Gwen made them both seem like morons. That said though another Peter Parker would just confuse people. That's not to say they don't reboot the back story and change some basic things about TASM 2. They need to change Osborn being dead, they need to change the whole Green Goblin Storyline. But if you recast it immediately becomes a reboot and it risks causing the problems that the Ed Norton recast did for the Hulk which is that it was not a very watched version of the Hulk, and still the least successful Marvel film
2. Introduce Spiderman on TV first: This to me is most important, introduce Parker, Mary jane, JJJ, and other intrinsic characters on AOS and the Netflix shows way before he pops up in a film. This will announce the connection but won't establish a connection specifically with those movies. Keep it vague. This will drive up interest in the TV shows, Explain the new york connection. And It builds interest in a possible Spiderman movie.
3. Have Spiderman (Not parker) show up in other movies: Not as an intrinsic character but be part of it. especially and Iron Man movie. Have Spiderman exist in their world and get interest up in the Marvel Universe.
4. Give Spidey his own movie and then kill off Peter Parker: this is going to be my most controversial idea. Spiderman needs a new story. There has been too many Peter Parker origin movies, and the big argument against parker in general is that Parker doesn't age, he never develops as a person. The One more day arc is the biggest example of this. What I propose is have a film where Parker is growing up getting married having a life finishing college and Miles Morales' origin story is told at the same time, at the end have Parker die and every subsequent Spiderman movie can be a young (high school then college) Miles Morales. YOu could also introduce Miles in the Luke Cage and Iron Fist movies as a side character on an episode without even making him a hero. This is valuable to the franchise because it immediately seperates Marvels Spidey from any Sony incarnation, it also allows for a Reboot in the distant future, and it avoids the retelling of the exact same stories from the first 5 spiderman movies. Infact the Spiderman film done my marvel could be called "Ultimate Spiderman" but I like the idea of calling it "Spiderman-the ultimatum" .
With these put into place i think the new Marvel Cinematic Spiderman would be off to a good start and could regain the public interest that has been obviously waining after the 5 films in 15 years that have also not all been very good, but allow interest in the character to survive for generations. Remember theres lots of SPidermen, not just Miles or Parker.