Is 100% antibacterial resistance possible?
This is a theoretical question, which I can't answer, because genetics is not my favorite topic. In practice we only have about a dozen antibiotic classes. There are already panresistant bacterias, which are resistant (as far as I know) all of these classes of antibiotics, so we have already lost.

The causes of our defeat is more interesting I think: 


Pharmaceutical industry does not have enough interest in the antibiotics research, since it is not as profitable as for example cholesterol reducers. Antibiotics are cheap, and you usually heal after the first treatment, while the research and the clinical trials are really expensive, it is hard to find working chemicals, which do not have severe side effects.  


  “We  need  to  shift  from  the  concept  of  the  pharmacy  as  a 
  ‘shop’  and  build  a  culture  of  pharmaceutical services. This is
  already happening  in some countries, but we need to make it  the 
  rule  everywhere,”  says  Zsuzsanna  Jakab,  WHO  Reg ional  Director 
  for  Europe.  “As  pharmacists  dispense  medicines  to  patients,they
  are   important  allies  in  our  fight  against  antibiotic 
  resistance.  As  such,  they  need  to  be  ena bled  to  deliver 
  accurate  information  and  counselling on proper antibiotic use.”
  
  Over  40%  of  antibiotic  prescriptions  are  inappropri ate,  recent
  studies  found.  This  relates  especiallyto antibiotics prescribed
  for the common  cold and sore throat; these most oftenresult  from
  viral infections,on  which antibiotics have no  effect. Further, in
  some countries, there is  atendency towards self-medication.
  Inappropriate an tibiotic use is the major driver of growing 
  antibiotic resistance.


Pharmacists have decisive role in combating antibiotic resistance, says new WHO European survey
People with Mycobacter infections does not always do the treatment long enough, so Mycobacters can become resistant to antibiotics.  


  Most people with TB are cured by a strictly followed, six-month drug
  regimen that is provided to patients with support and supervision.
  Inappropriate or incorrect use of antimicrobial drugs, or use of
  ineffective formulations of drugs (e.g. use of single drugs, poor
  quality medicines or bad storage conditions), and premature treatment
  interruption can cause drug resistance, which can then be transmitted,
  especially in crowded settings such as prisons and hospitals.


http://www.who.int/features/qa/79/en/
There is no global regulation of how to use antibiotics, so in some countries you can buy them without consulting a doctor and get a prescription. On top of this you can buy antibiotics without prescription on the internet if you want. This leads to overuse of antibiotics, and overusage leads to resistance.  


  Self-medication is more common in developing countries due to factors
  such as ready availability of antibiotics without prescription, the
  unrestricted access to antibiotics,lack of regulation over drugs, and
  physicians and pharmacists prescribing and dispensing antibiotics
  without regard to the cause of infection


http://article.sapub.org/10.5923.j.cmd.20110101.02.html#Sec3.3.4  


  We found 138 unique vendors selling antibiotics without a
  prescription. Of those vendors, 36.2% sold antibiotics without a
  prescription, and 63.8% provided an online prescription. Penicillins
  were available on 94.2% of the sites, macrolides on 96.4%,
  fluoroquinolones on 61.6%, and cephalosporins on 56.5%. Nearly all,
  98.6%, ship to the United States.


http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2746509/  


  These results demonstrate that, although illegal, the sale of
  antibiotics without a prescription continues in Spain.


http://cid.oxfordjournals.org/content/48/10/1345.full
Some of the antibiocstics are used by agriculture industry, which leads to antibiotics resistance as well.  


  They identified bacteria able to shrug off the drug of last resort -
  colistin - in patients and livestock in China.
  
  It is likely resistance emerged after colistin was overused in farm
  animals.


http://www.bbc.com/news/health-34857015  


  Nutritive and therapeutic treatment of farm animals with antibiotics,
  amounting to half of the world's antibiotic output, has selected for
  resistant bacteria that may contaminate the food produced.
  Antibiotic-resistant enterococci and staphylococci from animals are
  found in food when they survive the production processes, as in raw
  cured sausages and raw milk cheeses1. The broad host ranges of some
  plasmids and the action of transposons in many bacteria allow
  antibiotic-resistance genes to be communicated by conjugation between
  different species and genera2,3. A multi-antibiotic resistance plasmid
  from a lactococcus found in cheese provides a historical record of
  such events.


http://www.nature.com/nature/journal/v389/n6653/abs/389801b0.html  


  About 2/3 of the antibiotics are used in animals.


https://youtu.be/iLJAleLjJv8?t=3m47s


So the problem is with not enough motivation in development and the lack of proper regulation of usage. Regulation is the business of the politicians, so its their fault as always. :D