... generally speaking I was thinking whether it can make sense to launch a new coin, let's call it Slimcoin-Plus, with the same idea of PoB and with a swap premine for all the willing Slimcoin owners
Given the number of Slimcoin addresses in the top 100 that have been active in the last couple of years (
https://chainz.cryptoid.info/slm/#!rich), it would appear that the majority of Slimcoin owners are fairly comfortable with the approach of occasionally firing up the wallet in order to collect their accrued stake. I have contemplated your suggested approach but, given the apparent fact that the majority of the community seem to be uncomplaining hodlers, I find it difficult to see any significant demand for a new Slimcoin chain, which makes the personal ROI very doubtful.
I think people hodl without informing themselves about what's going on. They are also not participating in anything that has to do with SLM hoping someone else will solve for them or something will miraculously happen and the price of SLM will go up. And in any case it's free internet money for them till there is someone ready to buy on the market.
We don't have to incomodate them with anything new. If they are comfortable with the things as they are they can carry on like that for as long as it will last, anybody of us can also have a look into the things and adjust if there is something to adjust. Maybe someone of those people will like to work on developing SLM as well.
But in the same moment we'll have another coin, (like people that have BTC and BCH in the same time) that carries on the original idea of PoB and develops it into direction that can help it recover the community and the market price.
I'm thinking about it because we are near to PoD launch, which is the idea I was working on for the last years and I wouldn't like to see it failing or maybe much more successfully implemented by another community only because we are approaching the technical limits of SLM and nobody really cares about it's fate.