Before fully answering… here’s my disclaimer…I’m in the US so things are different here. But some of my experience may be helpful.
OP, I think you should start having the conversations now. Such as what their plans and expectations are, POA, and medical directives. You and your DH need to be on the same page too!
About 5 or 6 years ago I had 2 parents and 2 ‘adoptive’ parents that my DH and I had signed up to take care of. And so far have had 3 totally different experiences 😁. So really, just go into all of this knowing all plans can go to hell in a hand basket no matter what kind planning you do 😳
My mum got sick (cancer) and deteriorated really quick. I was 400 mi away so my hands on support was pretty limited. That being said I was able to manage her medical care effectively remotely. The hands on was more challenging. She had always said she was not going to be one of those old people who refused to give up their houses… she became one of those old people who refused to give up her house. In the end she probably only had 1-2 weeks where she needed a lot of hands on care. If my sister hadn’t been local I would have arranged for in home care from an agency.
My stepdad (again 400 mi away) at the same time was physically deteriorating (falls, mobility, not being able to care for himself). After a fall he went to the hospital, from there he went to an assisted living facility, where he’s been since. This place has care that ranges from assisted living to hospice. Effectively he’s the responsibility of the state now. The facility he’s at is a good one, the county pays for everything, the facility arranges for any medical appointments he has and provides both transportation and someone to go with him. I buy him stuff he needs from amazon. When he moved in surprisingly an old friend was also a resident, so she is also taking care of him. He’s now been moved to full nursing care.
And lastly, my 2 adopted parents are currently in independent living (I think this is similar to your sheltered living). They are local to us, so my DH and I have given more hands on support (a few doctor’s appts, sporadic calls to come over for a medical thing, tech support, etc.). We’ve discussed with them about their plans. Where they live has step care from independent living through hospice. They are not expecting hands on care but I expect we will be more actively involved in the next couple of years. These 2 are the poster children for the “I don’t want to be a bother”, so I’m not expecting them to expect us to take care of them 24/7. They’ve also been very proactive to set up their lives so that they will have the resources they need at each stage. DH and I knew what we were signing up for when we agreed to help them so no regrets.
I think you just need to be upfront with what you’re able to do and to expect some level of involvement. That being said don’t feel guilty or pressured to give up your life. I will be honest it didn’t feel great telling the social worker that my stepdad had no resources and no home to go to after discharge from the hospital. I also had to tell them that I was not responsible for him and was not going to move him in with me or care for him. I did tell them what I was willing and able to do but that was going to be limited. I had to tell my stepdad the same thing. All of his social workers have been great and have not pressured or guilted me at all. So you will have to be firm with your boundaries when it’s time for decisions to be made about care.
I joke with people my age when the topic comes up “Don’t be the responsible kid/sibling” 😁