Use of "¿" in Spanish serves a specific purpose, which is to indicate the beginning of a question which otherwise would be ambiguous as to whether it were a question or a statement:
Q: ¿Existen estudios sobre este tema?
A: Existen estudios sobre este tema.
You see, the exact same sequence of words can be used for the question and the answer. The "¿" is necessary to know how to interpret the sentence from the beginning. Therefore, even if the trend in informal communication is to omit it for whatever reason, I personally doubt that we'll see it being dropped from the language formally.
In English, this ambiguity is not an issue, because there is less flexibility in word order. You start questions with an interrogative word like "how", "what" or "when", or with the word "do". Also a question can be formulated by changing the word order to set it off as a question:
Q: Are there studies on this subject?
A: There are studies on this subject.
In Spanish the word order may stay the same and be grammatically correct. In English the order of the words "there" and "are" makes one a question and one a statement, and you know it right off the bat.
An anonymous user edited my answer to mention the following (which should have just been left as a comment, not an edit):
"Yes, but in English one can also ask:
There are studies on this subject? It usually indicates greater incredulity but it does serve as a question."
This is more informal language. Additionally, I'd wager that you'd come across this formulation in verbal communication more often than written. I'm not entirely certain if it is correct grammar technically, but I'm updating the answer because I agree that you will definitely hear this type of forumulation of a question (whether correct or not). I also agree that this type of formulation indicates a greater degree of incredulity. In fact, expressing a high degree of incredulity may be its only purpose. You would not formulate a sincere question in this way. Therefore, I stand by my previous explanation, and believe my points were valid.