I honestly don't think so - not the S reveal or the sudden rush of games. The S reveal has been rumoured for ages and nothing has come. Why should September be more reliable than the rumours of May, June, July or August announcements? If anything the passing time makes a September announce less likely.
But either way, the fallout from the July MS reveal has changed the scenery....
There's some rumouring Xsex will be delayed, it's clear it's gonna launch with not much in the way of system sellers and zero first party.
Even if the factors that could delay Xsex wouldn't apply to the S, I don't think MS is going to launch 2 consoles into a space with no software support and zero hype. That's just throwing good money after bad.
Then there's the games. There aren't gonna be first party games to show. There simply hasn't been time. We know what MS first parties are doing from the July event and they're nowhere near producing anything. AAA games take a long time - 5 years or so - to develop and MS first party are barely at the start of their cycles. With Halo delayed that's not gonna to get shown again until they know it's observably better. The rest are further away than that.
So, MS first party is gone for now - may as well forget they exist for 3 years when it comes to console releases.
Third parties? Well they've got (timed console exclusive) Medium - doesn't look particularly great but let's see, and Scorn with no confirmed release date, gameplay from back when it failed kickstart and a team who hasn't released a game before. Other than those a few other games which won't be on PS5 for a while, but I can't recall any titles that are going to drive a console launch, nevermind 2 Xbox consoles.
MS may be desparate to moneyhat something but if they have succeeded there'd be no reason to keep that quiet, so I assume they haven't got anything to say there either.
So in summary I don't think MS are suddenly gonna produce a rabbit from their hat - I don't think Sony is either. There's no reason to "hide" stuff - it's not chess, its about as complex as Snap now in terms of release strategy.
I don't even think they're holding back price and release details due to competition - I think they're doing it to mitigate risk from the impact of COVID on profitability - if they misjudge the costs and set the RRP too low, console profits are severely impacted. If it were me I'd wait until as close to launch as possible to find out what the effects of lockdowns and reduced efficiency are in the logistics and sales channels, coupled with exchange rate fluctuations and the potential for financial impact from recovering economies. I think that's why MS and Sony are dragging their feet on the specific launch details.