Does not an extension of the Church's liturgy to a class of persons have more significance?
If there are, draw out the implications. But there's no generic doctrinal statement regarding BoD in the Canon itself.
Certainly a Catholic burial COULD imply a possibility of salvation, but not necessarily. At best one could hold that this means that the Church remains open to the POSSIBILITY that such as these could be saved. Not everyone who receives Catholic burial is saved. So the Church, at best, allows the faithful to hope in the possibility of the salvation of those described here. Notice, too, that this is limited to formal catechumens.