The massive concentration camp population must have been considered for recruitment in the final years of the war, even if it contradicted Nazi supremacist ideology. Was there ever discussion of sending Jews or Roma or political dissidents to the front rather than just slaughtering them?
The Third Reich actually did recruit political prisoners into the Wehrmacht, even before the end of the war.
From 1935 onward having been imprisoned in a prison or camp, especially for political offenses excluded a person from serving in the Wehrmacht. This was instituted with the experience of the November Revolution in mind and should serve to keep the potential troublemakers and especially communists away from weapons.
For persons who had been sentenced for committing grave crimes or Wehrmacht soldiers who had violate discipline in a grave manner, before the war the so-called Sonderabteilungen existed which had harder and more difficult duties and served for people to prove themselves.
The same idea was instituted in the war later with the Bewährungsbataillone (probation battalions) of the 500 and 999 variety and the Feldstrafgefangenenabteilungen. The latter were in essence units of people sentenced for pretty much any crime that lead to a prison sentence and the idea behind the was to discourage people to avoiding the front by committing crimes.
The Bewährungsbataillone were founded in 1940 and 1942 respectively. The 500 one was for soldiers having committed crimes while the 999 unit was specifically for the group you asked about. Counting approximately 37.000 members the 999 unit consisted at least to 30 to 40 percent of former concentration camp inmates, from communists to social democrats to Jehovah's Witnesses and also a small number of Sinti who were given the chance to be freed from Auschwitz in exchange for serving in the German military.
The Bewährungsbataillone (it was not really a battalions as you can tell by the numbers but more like a division) first saw service in North Africa in 1943 but as anyone might be able to imagine with a unit full of political opponents of the Nazis, one of the first thing many of them did was to desert and seek out Allied troops, some of them even ending up fighting for the Allies for the remainder of the war. The same experience did occur when three of its infantry battalions were send to the Eastern Front in 1944. The bulk of the unit however remained in Greece where it was on occupation duty.
In Greece it also occurred that members of the 999 unit founded the Antifaschistisches Komitee Freies Deutschland (Antifascist Committee Free Germany) and deserted to the Greek Partisans wholesale. This makes for an odd case because this was probably the only coherent unit who fought for the Germans and the Allies and who as part of ELAS then continued to fight the British shortly after liberation in Greece.
Interestingly enough, the 999 unit saw comparatively less deaths of its members and less dangerous missions than the 500 unit but that certainly came down to them being - rightly - regarded as less reliable.
After mass desertion to the partisans, many communists were removed from the unit and transferred to the Buchenwald Concentration Camp. In September 1944 the Army leadership chose to not reinforce the unit anymore and so the unit was disbanded in May 1945 with five members remaining.
As for Jews, this idea was never considered. Regarded as the mortal enemy of the Germans and seeing how serving in the Wehrmacht was glorified in the Third Reich (the penal battalions were open to mostly Germans with the idea of them redeeming themselves), having Jews fight for Germany would have been outright rejected by the Nazis leadership. So while German political prisoners were forced to serve in the Wehrmacht, concerning Jews this idea never came up. There was some discussion on including "Mischling" resp. throwing those "Mischlinge" who served in the Wehrmacht out but those discussion sort of meandered around and never bore any fruition.
Hans Burckhardt, Günter Erxleben: Strafdivision 999. Erlebnisse und Berichte aus dem antifaschistischen Widerstandskampf. Deutscher Militärverlag, Berlin 1965. (GDR scholarship)
Hans-Peter Klausch: Die 999er. Von der Brigade „Z“ zur Afrika-Division 999. Die Bewährungsbataillone und ihr Anteil am antifaschistischen Widerstand. Röderberg-Verlag, Frankfurt am Main 1986.
Gottfried Hamacher, Andre Lohmar, Herbert Mayer and Günter Wehner, Gegen Hitler: Deutsche in der Resistance, in den Streitkräften der Antihitlerkoalition und der Bewegung "Freies Deutschland" Dietz, Berlin (March 2005).