As regards obstacles, the rule change may not make much of a difference because one patently cannot send QXC students in a C152 to a 500m grass strip with 50ft trees at each end The level of PPL training is not up to that kind of thing; performance planning is generally poorly taught. Training, especially solo flights, will have to go to nice and easy places.
It seems to me that part of the problem is that almost by definition licensed airfields are larger with easier approaches, so currently there is no opportunity or need to teach approaches at sub 500m grass strips with obstacles. I learnt at Norwich with > 2000m of runway and didn't seriously do short field until I converted to tailwheel and started using small grass strips.
This proposal is long overdue and places the onus on the airfield operator and the instructer to make a judgment, which is the way it used to be! It is also the way a lot of regulation in the professions is going, with detailed rules being replaced by broad principles which should be followed, leaving more discretion on their implementation to individuals.
This could have a significant positive impact on the cost of training and if they eventually allow PPL training for remuneration without having to have a CPL then this will further improve the situation. Will we see a rear guard action being fought by existing training organisations who will have cause to fear this proposal?!