"Please note that Lubuntu 12.04 is not an LTS (5 years support), but a 'standard' release, supported for 18 months. This is simply due the fact there is insufficient 'man-power' to commit to 5 years of support."

Source: https://wiki.ubuntu.com/Lubuntu

There is a possibility of LTS for Lubuntu 14.04: https://lists.ubuntu.com/archives/lubuntu-users/2013-April/003941.html

Next steps are 13.10, and 14.04 which should be a LTS version for Ubuntu. Last LTS (12.04), I considered that we were not ready for such commitment. I was also unsure of the work needed to make a good LTS. With more experience, I have now a better vision of this goal.

So, let's make it simple, I would like Lubuntu 14.04 to be a LTS version.

But claiming we want a LTS its' not enough. First, we need to make it stable enough, so we can safely claim it's a LTS, because people who install a LTS want a stable system. But, I also would like to make it sexy enough to be proud of it, to make people happy to recommend it. I would like to make it THE release of Lubuntu, the reference of all Lubuntu releases. To achieve it, I have several goals in mind, items that I consider we need to finish for the LTS, and I think we can finish them ...

Read more about Lubuntu's future here: https://wiki.ubuntu.com/Lubuntu/Testing/14.04

Analysis

The WineHQ repository misses the dependencies for wine-stable package.
I have reported a bug 48513 to WineHQ bugzilla.

^{The main problem here is bad documentation, which is written in non-reproducible way.
The Rosanne DiMesio's main idea is "People who don't bother to read the directions are always going to have problems.".}

So we need to write our own documentation until WineHQ-officials become smarter.

The problem with dependencies was caused by the FAudio dependency, which is not contained in Debian/Ubuntu and WineHQ repositories. We can determine the exact package name by using command below and analyzing of their output:

$ sudo apt-get install wine-stable-amd64
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 wine-stable-amd64 : Depends: libfaudio0 but it is not installable
                     Recommends: libcapi20-3 but it is not going to be installed
                     Recommends: libodbc1 but it is not going to be installed
                     Recommends: libosmesa6 but it is not going to be installed
                     Recommends: libsdl2-2.0-0 but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

The aforementioned libfaudio0 package is available only for Ubuntu 19.10 and upcoming 20.04 LTS.

Solution

We need to follow official WineHQ guide for Ubuntu partially:

sudo dpkg --add-architecture i386
sudo apt update

Note: if you have WineHQ repository added - remove it with

sudo apt-add-repository -r 'deb https://dl.winehq.org/wine-builds/ubuntu/ bionic main' 

to prevent the mess of repositories and then proceed.

Then we need to add other repository from OpenSuse Build Service to get libfaudio0 installed:

wget -q https://download.opensuse.org/repositories/Emulators:/Wine:/Debian/xUbuntu_18.04/Release.key -O Release.key -O- | sudo apt-key add -
sudo apt-add-repository 'deb https://download.opensuse.org/repositories/Emulators:/Wine:/Debian/xUbuntu_18.04/ ./'
sudo apt-get update

and only after this install one of WineHQ packages:

# Stable branch     
sudo apt install --install-recommends winehq-stable

#Development branch     
#sudo apt install --install-recommends winehq-devel

#Staging branch     
#sudo apt install --install-recommends winehq-staging