EMT has some of the longest journey times incomparison to other inter-city operators when you compare journey times to distance. This is due to the line speeds and capacity. They have made some big improvements to train times in recent years, but I barely think they will be prepared to have 80% of their services calling at LLA Parkway.
They will have no say in it as the new franchise agreement will be the bible as to how many trains stop per hour. Trains operators will then bid to run the service as laid down by the franchise requirement which will extend to several hundred pages.
Saying that the Thameslink franchise specifies 2 trains an hour running through the night but that doesn't happen as many of the trains are cancelled allegedly due to a driver shortage.