Isaiah Bradley, while also ensuring it endures as part of the present and future thanks to the Flag-Smashers and the experiments of Dr. Nagel.
On top of that, though, is the promise of yet more Super Soldiers to be created. There are still 12 vials that remain uned for, which means there could be up to a dozen more Super Soldiers made in the MCU. Exactly who they will be (if it happens) remains unclear, but the clearest contender is John Walker, the replacement Cap who has already shown he'll do whatever it takes to live up to the standard set by Steve Rogers, even if that itself means he is destined to fail.
There are some clear similarities between Walker and Steve that show just why he was chosen as the new Captain America: both men prove themselves to be incredibly loyal to their country, and ready to make the ultimate sacrifice in order to protect it. However, they also have obvious differences in their ideals, and just how far they're willing to push things, and it's those differences that will likely define just how Walker compares as a Super Soldier to Steve Rogers. Indeed, it could be said that Walker will very much be the direct opposite of his predecessor. When being given the serum, Abraham Erskine tells Steve to be “not a perfect soldier, but a good man." Steve lived up to that until the very end, even to the point of it costing him the shield, but Walker is the inverse: he is not a good man, but he is the perfect soldier.
The Super Soldier Serum enhances that which is already inside a person. Steve Rogers was not a great soldier by the most immediately evident metrics - he was skinny and frail - but on the inside he was brave and his heart was truly good, and they're the qualities the serum amplified: quite simply, good became great. Walker, on the other hand, is very much the ideal of what a soldier should be, as even without the serum he is strong, athletic, an incredibly skilled combatant, and a smart tactician, receiving three Medals of Honor. At the same time, though, he has already shown he has an inflated sense of ego - made worse by becoming Captain America - is incredibly quick to anger, and may well be scarred by his battles in ways that could have further consequences if unchecked.
It's fair to say, then, that the Super Soldier Serum could make the Steve Rogers was as Captain America.