I have blood samples stored on FTA cards for around 5 years and it would be great if someone could share his or her experience with such samples for NGS.
We are working with whole genome sequencing of RNA virus (~ 15kb) extracted from FTA cards on the illumina MiSeq. We tested several different extraction methods, but not chelex, and obtained good results with all of them. Because DNA is more stable than RNA, I presume that you will get good results too. Good luck!