From a developer point of view, what assurances (regarding
security/bug fixes) can we give to current clients to stay on magento1
even after 2018 and not switch to a new platform?
Well, you can't give any assurance regarding security and bug fixes as they won't be anymore releases/patches for M1 from November 2018.
Also, if by "switching to a new platform" you mean "going from Magento 1 to Shopify (for example)" then, depending on the level of customization of your M1 store, it'll be cheaper to migrate to M2 IMO.
Now, there's 3 different cases from what I've heard from the community:
- First, there's the ones who will migrate from M1 to M2. The migration process will get smoother over time as more and more people will do it and understand the indepth mechanism of it.
- Second, there's the ones who will not migrate to M2 anytime soon but will use the money they saved by not doing the migration to hire a part/full time security consultant to ensure their M1 store stays safe.
- Finally, there's the ones who will not do anything for several reasons: first reason being "they're not aware of M1 EOL and haven't done patches/upgrades ever" (and the fact that people are not educated enough is probably the biggest problem in IT security). Another reason is that they can't afford either the migration or the security consultant.
From similar experiences on other platforms did the community/hosting
companies keep focus on the old version and continued to offer
There is already one unofficial repository which is community driven and which goal is to be the Magento 1 LTS you can find it here: https://github.com/OpenMage/magento-lts
I haven't heard about similar experiences on other platforms simply because Magento 2 is way more than a V2 of Magento 1. It's a different software even though it originally was a port of M1.
Regarding hosting companies, I highly doubt they will stop supporting Magento 1 anytime soon after EOL. As a comparison, I'm pretty sure a lot of hosting companies still run PHP 5.5 even though EOL was a few months ago.