A lot of companies are working on allogeneic CAR-T, CAR-NK and TCR-T products (from healthy donors and/or iPSCs). With these you can produce 100s-1000s of doses in a single run, greatly reduce costs (data from FATE and NKTX back this up) , there will be improved consistency between batches, and they may have better activity [2,3]. AUTL will be move their first version forward in Q4 and add two additional transgenes to stop GvH  and HvG (rejection).
In terms of (S)AEs (CRS and neurotox) then there are ways to reduce them for hematologic malignancies. GILD is in the clinic  and will likely use SGMO's ZFNs to KO a certain gene as well .
4 https://ashpublications.org/blood/article/132/Supplement 1/700/266123/A-Protein-Based-Method-to-Develop-Allogeneic