completing the PCT in a single season is more a mental thing than anything else. If you're motivated and keep your motivation up during the hike, nothing will prevent you from getting there except for something catastrophic which is always a possibility but not the rule.

That said, some factors that seem important in vanishing motivation from thru-hikers who leave the trail are related to wrong expectations. A PCT thru-hike is probably not the best thing for a first time experience in backpacking, probably not even for a first in long distance backpacking. I think people who know what they're doing and what they're getting into usually make it through with no major problem. It's hard work but not technically difficult.

I don't know your level of experience but you've got time anyway so get out there, try things out on the field. Fancy gear is a nice thing to have but in practice anything works if you know how to make it work and you enjoy what you're doing. With time, you'll fine-tune your gear kit to match your likes, dislikes, style and budget. Like with your question about footwear... running shoes are most common among thru-hikers on the PCT but that only means it can be done, not necessarily that'll be the best for you. You have to try and see for yourself. It's not something you need to know three years in advance anyway.

I'd highly recommend getting used to your gear kit for the PCT before the trip. At least, avoid trying any new major item on the PCT thru-hike. It's important to trust your gear, it gives you confidence and that helps with the motivation.