Oliver Cowdery originally wrote hopes here in 𝓞 (“having no hopes of meeting them upon fair grounds”). But it is difficult to tell whether Oliver wrote a defective s at the end of hopes or whether he tried to erase the plural s. Later, when Oliver copied this passage into 𝓟, he interpreted the word in 𝓞 as hopes and copied it as such into 𝓟. All the printed editions have retained the plural hopes.
Elsewhere in the original text, there are 39 instances of the singular noun hope, as in Alma 13:29: “having a hope that ye shall receive eternal life”. But there are also six other instances of the plural hopes. In fact, in two of these cases, we can see the tendency to replace the unexpected plural with the singular:
The four other examples of hopes are invariant in the textual history:
Thus the plural hopes is clearly possible here in Alma 52:21. The critical text will accept it since it is the reading in 𝓟, the earliest fully legible source for the word; although 𝓞 is extant, one cannot be sure whether the plural s was defectively written or erased.
Phrases with the plural hopes like “no hopes of X” and “without hopes” were common in the 1800s, and examples can be found dating back to the 1600s, as in the following examples found on Literature Online (accidentals regularized):
The use of the plural hopes in the Book of Mormon is perfectly acceptable even in the unexpected cases of “no hopes of X” and “without hopes”.
Summary: Maintain in Alma 52:21 the plural hopes, the definite reading in 𝓟 and perhaps the reading in 𝓞; usage elsewhere in the text supports the possibility of the plural hopes (as originally in Mormon 5:2: “I was without hopes”).