Will daily suggested workout feature be supported on fenix 5 plus?

That would be nice. But how often do Garmin add features to anything other than the latest product line? 

Quite often I think.

Garmin Coach for example - that is a new feature made awailable also to a bit older watches. And I hope this to be as well...

I guess it is not coming to the Fenix 5 or 5s since it's been over a year and still not here.

Is there any other app that we can use to get this functionality? I do coach guided plans sometimes but it would be nice to have just a suggested workout when you are not necessarily training for a race ¯\_(ツ)_/¯

There is no real need to add such a feature to the watch.  Open Garmin Connect on a computer. Under the self-guided training plans there are the "Improve your fitness" plans which should do the job for you.

I was looking for something more dynamic like J alluded to below. I have never tried that "Improve your fitness" as it seems appropriate for me coming out of my winter hibernation. 

As for the business side of the decision not bring this feature to older devices, I honestly feel cheated by this type of tactic. I know others in tech do this kind of thing but it is normally backed by the feature being too resource heavy for the device. In this case, there is no reason to not have it since it is all done in the app (just like "Guided Training"). It is hard to believe that after paying nearly $700 for watch they would start to nudge you to a new device after just 2-3yrs

Excuse the rant in that last paragraph..... As you can probably tell, I am not happy

Technically there is no reason garmin can't do it.  But really is there a reason to rant?  Its not on the list of advertised features so shouldn't be expected.  Its not a tactic - its common sense.

I totally agree and believe that Garmin is one of the worst offenders here. Think of all the resources wasted on having to get new watches for new features on hardware that still works.