Hi! So cool you want to test this out! And I'm all for people using what they want from my guide and changing what they don't like or what's not working for them, so go for it, mate!
I encourage you to try it out your way, but I'm gonna address the points you raise;
First of all, releasing every player from the roster of the team you're replacing
after season 1 gives you a much larger number of free agents than normal (I don't know how that would affect AI decision making if at all) and an unrealistic amount of
good to great free agents depending on the team you're replacing (but even the lowest rated teams in Madden have several 80-99 OVR players). Although I haven't tested this, I think it's reasonable to assume that with the salary cap which limits teams ability to sign high rated players will leave a lot of great free agents either unsigned for the next season or give you an unrealistic amount of good free agents to sign with no competition (which depends on your house rules for free agents). In my personal opinion the core of my expansion franchise, even though it's not gonna be very good, should come from the expansion draft, not the first free agency. If my best players all come from free agency, it sort of defeats the purpose of the expansion draft in the first place.
But even if you only limit yourself to lower rated free agents, it's likely that the other NFL teams are focused on the influx of higher rated players leaving no competition for you to sign who you want.
Secondly, what’s the story behind your expansion franchise? I’m not saying you have to put a lot of thought into a backstory or anything, but as I said in the guide itself, letting the team you’re replacing play out the first season and then move to a new city sounds like a
relocation, not an expansion, which is exactly what I didn’t like about my old method and why I came up with this guide in the first place.
Additionally, if the NFL were to introduce a brand new franchise, that’s usually a process that takes a couple of years (like with the Texans who were awarded a franchise in October, 1999 and didn't join the league until 2002) so I know I’m already pushing the boundaries for what’s realistic by having an NFL team fold right after the 2015 NFL playoffs and have a new expansion franchise ready to play at the start of the 2017 season, just 18 months later. By using your method, you’re basically having a team dissolve after the 2016 season and expect a brand new franchise to be ready to go in a new city with a stadium that’s up to NFL standards in just 6 months. Personally, I don’t find that option more realistic than what I’ve laid out in the guide. The NFL functioned fine with only 31 teams before the Texans joined so I'm sure they would manage 1 season
Now I’m not saying there’s anything wrong with your method and you should do what’s best for you, I’m just pointing out that one of my main goals of this guide is to come as close to an actual expansion of the NFL as I could which in my opinion requires a league of 31 teams to
expand to 32
Regarding your top ranked players playing for other teams in season 1, I don't see that as a problem or unrealistic but I think it depends on your point of view and which story you're telling. In my mind – and dynasty – a team folding after the 2015 playoffs would have to release their players from their contracts. These players would find new teams during free agency and through preseason/training camp before the start of the 2016 season – or the first season in franchise mode – and play for those teams. I don't see how that's more unrealistic than basically doing exactly the same thing only a year later? And by releasing them in preseason in season 1 (except for the players I manually move before starting the franchise), teams have a chance to improve and these players will have stats for teams that are actually competing in the NFL and not a franchise that is basically "dead" (since they're folding at the end of the season anyway) and forced to lose every game (to get the #1 draft pick).
All that being said though, remember something else I wrote in the guide;
«As long as YOU’RE having fun, my opinion on what’s realistic and fun and what’s not shouldn’t matter at all. So do your own thing!»
Hope you have fun with it and please feel free to update us on how it's working out for you