Ruben Loftus-Cheek recently injured his ankle in a friendly.
The player who is quite injury prone is now out for possibly more than 6 months and will miss the national camp when England enter the Nationals League final.
“We will find out more about a couple of players in that period and then I am going to have to make a couple of decisions,” Southgate told reporters.
“But we can change if we have injuries after that date. Frankly there is every chance that is going to happen.
“We have just got to make the best possible decisions really with the information that we have. It is constantly moving.
“I went to bed last night and Ruben is in the squad and playing brilliantly and now it is a huge disappointment for him. He misses now a major European final and a brilliant opportunity with us.
“In particular he has really come on in the last few months and looked strong and playing with a lot of confidence and I am really disappointed for him in particular.”
RLC will be sad also to miss the final of the Europa League with Chelsea against Arsenal.