This should be viewed positively. SInce hearing aids will be more accessible to the public, the cost of prescription hearing aids will be more affordable and the quality would be better. This would increase the awareness of the public to go for screening for deafness of hearing impairment, will get the prescription and buy over the counter.
This is like the availability of reading eyeglasses over the counter. People will have substitute hearing aids, probably some will have 2 or more spares, they can clean the alternative hearing aids, so the availability should not be a threat but should be taken as a challenge for hearing manufacturers for better quality service and better erformance on the hearing impaired who can now access affordable hearing aids

The future of OTC hearing aids is quite good for patients as they can easily buy it over the counter without any prescription. Those with difficulty in hearing can buy it easily. Also, due to compitition, the price will go down.
The downside of OTC hearing aids:
Patients with hearing difficulty will directly buy it over the counter instead of consulting a doctor.
Due to high compitition the quality of the hearing aids can not be assured from various manufacturers.

I view this as a potentially good thing, but for an unobvious reason other than the ones already posted... there is a proven correlation between hearing loss and cognitive decline. That is, hearing loss is a precursor to cognitive decline. i don't know if the two are directly related, that is, if hearing loss is averted, cognitive loss can be prevented. However, if they are, OTC hearing aids could potentially help people at risk of cognitive decline due to hearing loss to remain more vital.