Load() and with() features, will they stop?

I don't believe anyone can really answer this question, even Appian employees are likely not to know (please speak up if I'm wrong!) but given how ubiquitous the use of load() and with() has been in the past it seems very unlikely that this will occur.

Is it possible, well yes. To me it seems unlikely though.

Always a possibility but it hasn't been done yet. To be honest, I haven't seen load/with in apps developed in the last 5 years though older apps developed before that might still be using it.