The most persuasive piece of evidence against her is already excluded - the alleged confession/false statement to police. Then you have the DNA - and the "excuse" to exclude that is VERY strong - many experts, including 2 independents experts- said it is not reliable.
Without those 2 - one of which is already excluded and the other one of which would make the Italian justice system look pretty silly not to exclude - you are left with a very weak circumstantial case. For such a case to work, juries want a motive, you don't have that here, you would have to believe someone decides to join a murder with a perfect stranger just for kicks. I am not sure if that ever happened before especially where there is not already a motive for murder like competing for same guy, etc.
The hand written letter is still in evidence
From page 72 of the SCC report:
6 ‐ The failure to [properly] evaluate KNOXS handwritten letter
The observation of the Prosecutor General is correct with regard to the failure [of the Hellmann Court of Appeal] to [properly] evaluate the letter written in English by Knox, which was translated and contained in the appeal files and which was already considered fully admissible by this Court [53] in decision no. 990/2008, it being a document coming from the accused, who wrote the letter voluntarily and in a moment of solitude (i.e., after the alleged pressure on the part of the investigators had ended) with the intention of defending herself, [and] pursuant to article 237 of the Criminal Procedure Code. In this letter, the young woman, without even wanting to clarify to herself and others the sequence of actions carried out the evening of the crime (perhaps I checked the emails, perhaps I read and studied, perhaps I made love with Sollecito...), admitted only to having smoked marijuana, to having had a shower with Sollecito, and to having dined very late; and then, placed herself in a dimension more dreamlike than real, writing of having seen herself crouching in the kitchen, with her hands over her ears, because in her head she had heard Meredith scream, even though these things seemed like a dream and she was not sure that what had appeared to her had really happened. She also added a very perplexing detail, that of having seen blood on Sollecitos hands; but she says she had the impression it was blood from the fish (most likely cooked for dinner). Her presence crouched in the kitchen when she heard the victims scream and the presence of blood on Sollecitos hand (linked to the aforementioned fish) are facts disclosed in a perplexing sequence, unless we interpret them as an attempt at clarification and as an admission of her presence in the house, which she reaffirmed when she specified that she saw Patrick (Lumumba, indisputably falsely accused) near the front door. She concluded her letter by saying that she didnt remember with certainty whether she was at her house that night.
It is indeed true that these reflections are of dubious substantial meaning, but it is also true that they cannot be dismissed as they were based on the presupposition of psychological pressure to which the author was subjected and of some mental manipulation that was exerted, first because the letter was written in complete solitude after the so‐called excesses of the interrogation and second because that same document was used by the Second Instance Court itself as the probative basis for the crime of calunnia, on the assumption of the full possession of her mental faculties, such that Knox was found guilty on the basis of this very letter (as well as on the basis of what she told her mother, once again in the full possession of her mental faculties, free from pressing interference, in the course of a conversation with her).
On this point there is, therefore, an obvious contradiction in the evaluation of the same evidence, which calls into question the structural coherence of the decision: on this basis, the judge of remand will have to formulate a new judgment with more coherent argumentation, the issue once again being a significant passage of the justifying argument pertaining to the presence or lack thereof of the young woman at her residence at the time of the murder.