Yup. Ashok Leyland does seem to be on their way out.
I was looking at their site few weeks back, and was surprised to find ALM 370 engines still listed (in the marine engines section). They may be "tried and tested", simple and rugged, but they simply are no match for the modern turbo engines.
We had a fleet of heavy vehicles, mostly AL, and I was the "unofficial" liquidator for the family business. (being AL was NOT the reason for the losses).
Typically, in those days, AL heavy vehicles returned a FE of 4.5 - 5 KMPL, while Tatas had a FE of maximum 3.5 KMPL, on Kerala highways. In city driving (2 decades back), the figures were 2 0 2.5 for AL and 2.75 to 3 for Tatas - IIRC, 1210 chassis). Obviously, AL was the vehicle of choice for long distance operators and tatas were the chosen vehicles for short haul and city driving. Even now, you can see that most long distance vehicles in Kerala are from AL.
AL was very innovative, almost ahead of times. They had brought in the Hino engines, full syncromesh gear boxes, overdrive was available as an option, and had even launched rear engined buses (those still run in Chennai city service).
Tatas started their fightback with the Cummins engine. Stage 2 in the fight back was pricing the cummins engined and Tata's own engines on par. ;-)
I had successfully finished my job by stage 3, so not sure of what happened afterwards!!!
There was another reason for AL being the vehicle of choice for long distance / luxury operators. AL vehicles had zero body vibrations. (remember that most heavy vehicle bodies in India are custom built). Tata vehicles, even those with best bodies, like TVS or Allwyn (remember that company? "Hyderabad Allwyn" - had some of better bodies for city service vehicles) would vibrate when the vehicle was idling at stops, and harmonic vibrations at certain speeds was common.
Today, operators in Kerala still prefer AL for long distance routes, and stick to Tata vehicles for short haul.
The Ker SRTC is a bit more smart. While I do not have any figures, I find that more vehicles from Ker SRTC are from Tatas. And on a recent trip on a brand new Ker SRTC express bus, I was like

looking at the instrument cluster in front of the driver. There was an RPM meter, and 7 or 8 other smaller meters. I cofness that I have no clue what those could be. I can guess meters like Oil pressure guage, ammeter, air pressure, fuel, probably brake fluid, engine temperature guage, etc. But there were still two or three meters unaccounted for, and I unfortunately could not have a closer look. Driver's seat, steering wheel placement, and instrument cluster were very comfy. In fact, tata heavy vehicles nowadays have a distinctly smaller steering wheel than what they used to have. There is no body vibrations at idle rpm. There is absolutely no harmonic vibrations at any speed (the vehicle touched 100 KMPH).
The Instrument cluster on brand new AL vehicles are still like what I had on our vehicles, whicl were solf off before 1989. There still continues to be the speedo, ammeter (battery charge indicator), air pressure guage (for air brake), and oil pressure guage. That is it. The steering wheel continues to be same size. Driver ergonomics is conspicious by absence (how does a non-adjustable steering parallel to ground look like?)
"All those meters would not be used anyway" is simply no excuse - even the drivers are becoming sophiscated nowadays.
In short, while AL is still where it was 20 years back, Tatas have moved on. Innovated. Even when vehicle bodies are totally custom built, Tata's insistence on selling vehicles with full front "cowl" (fully built front end, with grille, engine cover, and driver's seat in place) has meant that they are able to ensure a standard driver seating position.