The aim now for City is to secure second place and regroup sufficiently over the summer to launch a stronger challenge next season.
With the FA Cup still to play for this term, City clearly remain in good shape and Platt feels they will be even better next time around.
The former England international, Roberto Mancini's first-team coach at Eastlands, said: "The potential is being realised.
"It is a very good team, it is a very good football club. It is not going away.
"That is the main message, not just to come out of last night, but forever.
"Regardless of what happens in the league this season, we aren't going away.
"We will be there next year and long may that continue. We will keep getting stronger and stronger."
The manner of City's performance in securing back-to-back wins at Old Trafford for the first time since 1972 prompted many to wonder how they had allowed United to go into the game 15 points clear.
City gave a committed performance and stifled United's attacking threat.
They claimed the lead early in the second half with a deflected strike from the impressive James Milner after Gareth Barry had robbed Ryan Giggs and fed inside to Samir Nasri.
United produced a quick response as Phil Jones forced an equaliser off Vincent Kompany from a wicked Robin van Persie free-kick, but Sergio Aguero settled the contest with a sublime individual strike.
Platt said: "More than a fantastic result, it was a terrific performance.
"You are never going to dominate a game for 90 minutes against Manchester United, but we restricted them to very few opportunities.
"The opportunities they did have were on the counter-attack, which you expect from a team like them, but we took the game to them, we had territorial advantage, we created opportunities.
"We were composed throughout, which was a good thing. But not only that, we showed character as well. Having conceded the goal to go 1-1, we showed the character to continue, to go and finish it off with a great goal from Sergio."
Platt accepts the result will probably only delay United's crowning as champions, but he felt it was important to have given the supporters bragging rights for the time being.
He said: "It is not mathematically impossible, but I think there are insufficient games. But to go there and perform in the manner we have done – Robbie (Mancini) has dedicated it to the supporters, which is nice. It's their night.
"It's 12 points and when they wake up in the cold light of day, it's still a massive mountain to climb.
"I don't think Manchester United will fail to get over the line, but at least they (City fans) have got the pride."
Despite the league situation, Milner has promised City will fight until the end regardless of whether the title is out of reach or not.
With the FA Cup still in the club's sights for a second time in three years, City do not want to ease up in their run-in.
Milner said: "Maybe the title is a bit out of reach now, but that changes nothing to us – whether it is or it isn't. It is still mathematically possible.
"All our concentration is on winning every game from now until the end of the season. Hopefully that will get us at least one trophy."
Aguero's brilliant goal, after coming off the bench, evoked memories of his famous title-winning strike against QPR on the final day of last season. It was a reminder of City's champion quality and Milner said: "He is not bad, is he? He is so sharp around the box. His composure and his finish at the end was superb. It gave us a deserved win."
City's attention will now turn to their FA Cup semi-final against Chelsea at Wembley on Sunday.
"It is a good springboard to go into the semi-final," added Platt.
City have a fitness concern over playmaker David Silva, who was forced off in the closing minutes with a hamstring injury and is rated doubtful for the weekend.