It can't support lossless audio unless Apple invents a new radio standard. Sony's LDAC is ALMOST cd quality. Or Apple places a stronger transmitter to allow WiFi bandwidth for audio. Or Apple places memory chips in the headset to buffer a stream.
If AirPods Max were suddenly going to gain even near-lossless audio via a firmware update, I'm sure Apple would have been hyping that all over the place on Monday. Instead, they only mentioned an update for the HomePod mini (and presumably the full-sized HomePod, but of course they're not talking about that anymore).
I'm hoping that Apple is at least working on something like AAC-SLS, which is similar to LDAC without being proprietary to Sony (which is why Apple will almost certainly never adopt LDAC directly). AAC-SLS would provide scalable near-lossless quality, which means that much like LDAC it could ramp up to almost 1Mbps at short ranges, while scaling down to the more traditional 256kbps when the signal isn't strong enough to maintain a higher bitrate.
It would provide near-lossless quality for most users as long as you keep your iPhone nearby when listening. Frankly, considering how few people can even tell the difference between 256kbps AAC and CD quality on most tracks, I suspect almost nobody could truly tell the difference between a full AAC-SLS stream and true lossless.
That said, Apple clearly wants to be as precise as possible when describing its Lossless Audio. Consider that it doesn't officially support Lossless Audio on the AirPods Max over a wired connection either. However, that doesn't mean you're getting 256kbps AAC when using the 3.5mm to Lightning cable. Rather, you're getting the exact analog audio stream that comes out of the headphone jack or DAC — it's just that it has to go through another ADC level before it's delivered to the drivers on the APM. That technically changes the stream, potentially adding artifacts, but it doesn't compress the audio or lower the bitrate — it simply converts it back to digital.
What's more of a mystery, mind you, is why the Lightning port on the APM doesn't support a straight digital stream from the iPhone's Lightning port.
I believe Apple will release a software update to AirPlay that will allow it to use both WiFI and Bluetooth together when paired with AirPods Max/AirPods Pro.
Unfortunately, since the AirPods Max don't have any Wi-Fi hardware, that would require an entirely new product. The current AirPods Max will likely never be able to support truly Lossless Audio — at least not over a wireless connection.
In the case of the HomePod and HomePod mini, Apple is updating them to pass ALAC directly over AirPlay 2. Right now, they use the 256kbps AAC codec to save bandwidth, but AirPlay 2 is technically capable of 24-bit/44.1kHz audio. They'll never provide Hi-Res Lossless, of course, but I seriously doubt that anybody would ever be able to hear that even on the original full-sized HomePod, much less a HomePod mini (which is the only speaker that Apple cares about right now anyway). In fact, I'm skeptical that even standard lossless audio is discernible from 256kbps on a HomePod mini, but it will be a nice bonus for those who want to think they can hear a difference 😏