Fire Emblem was saved by Awakening because Nintendo woke up to the fact that the games were incredibly niche due to their gameplay. Here's how Nintendo turned things around:

-Difficulty settings: Aside from Sacred Stones, the standard adventures are fairly hard. Strategy games usually have a high learning curve to begin with and the Fire Emblem games could go from zero to brutal pretty fast. More people will be willing to stick around if they aren't getting their ass kicked by the 5th chapter.

-The ability to turn off perma-death: nothing quite kills your motivation like seeing one of your favorite characters permanently die and knowing full well that it was your fault. This was a turn off for a lot of players, even for some of the more dedicated fans. I guarantee you that if Pokemon worked like Nuzlocke runs, it would have maybe a quarter of the fans that it has today.

-Character immersion: creating a customizable avatar that was actually involved in the story and making support conversations significantly less tedious were probably the smartest changes they made. It made Awakening a lot more memorable and made it easier to get attached to the characters.

-Shipping as a literal gameplay mechanic: Nintendo drove a syringe into gamers' id with this one. Sometimes totally shameless and cringe-worthy but almost everyone secretly likes shipping to some degree and Nintendo went into overdrive with it.

Awakening REALLY saved this series' ass.