I do agree that this move will be a disaster for QR in the medium-term unless they change policy. I think they could get away with the seating change (as BA did, albeit with some negative publicity at the start), but dropping lounges or making some business passengers pay for lounge access is just a PR disaster in the making for a number of reasons:

• Some travelers will not notice that the fare does not include lounge access (I note they do now say "Lounge access not included" in the Classic/Comfort/Elite fare select page, but it would make it more impactful if they put a red X through the icon to highlight it's different to the other fares)
• Corporate travellers will often have to book the lowest business fare - I'm not sure if it will be obvious when booking through corporate booking tools that lounge access will not be provided
  • Both of the above points will result in lines of bemused travellers at lounges, followed by Facebook/Twitter exchanges where they tell all their friends and followers how cheap QR is by not providing lounge access for business class tickets! This will impact the perception of QR's business class offering overall
  • It's previously been an issue in Doha with blockages at the Al Mourjan lounge escalators just from the lengthy explanations as to why people with OW access have to use the separate Business/First lounges, but it will be many times worse going forward with this new policy!​​​​​​​ So it won't just impact the experience of those denied access, but also those allowed access.
• ​​​​​​​Travelling QR results in a forced transit in Doha, so it's not just losing lounge access at the start of the journey, but also the mid-point transit
• If I knew I would not have lounge access I will be much more inclined to arrive at the airport as late as possible - if more passengers do this it will put more strain on the check-in and baggage processes and could have an impact on QR punctuality, etc

I have OW Emerald status, so should be able to get seats and some lounge access in most locations. However, moving forward, I will now be much less likely to choose QR over another airline. A key differentiator for me has been the lounge experience, especially their premium lounges such as LHR. I will also be interested to see how premium travel agents and package tour companies respond - since they have traditionally highlighted the airline lounge experience as a key part of the journey.