You got to be kidding right? There is some industries where (while sure the start-up cost is heavy) there will ALWAYS be competition. You'd be kidding yourself if you thought Apple and Samsung merging would cause prices to go through the roof. People would choose other products if the price wasn't justified.
You'd be kidding yourself if you thought Apple or Samsung could and would buy up all the phone manufacturers in the world.
If legally samsung and apple could merge then we can assume they can acquire any company they like then yes absolutely I would expect them to buy out any other competitors and create a perfect monopoly.
Truthfully though, this is exactly why I hate the government. I understand laws are there to "protect the consumer", but honestly government has no business being involved with private businesses outside of taxes and thing like that. They should not be able to tell private business yes you can merge, no you cannot, etc.
Go to a grocery store. Nearly every single item in the store is owned by one of 10 mega-corporations (Coke, Pepsico, General Mills, Kellog, Mars, Unilever, Johnson and Johnson, P&G,. Nestle, Mondelez). Now imagine those condensed down into 4-5 ultramegacorporations. Competitive pricing would disappear overnight. Suddenly they can charge whatever they want for food items because there is no real competition. Those corps already own all the organic products also so you are left with store brands and do you really think Walmart, one of the worst corps in the world, would bat an eye at raising their prices on Great Value brand products if there is no incentive at all for bottom out the price to compete in the market that exists now? Now apply that to phones and tech products. Apple already charges a laughable amount for their products, especially computers. If they bought out Samsung that kills them from the computer, tablet, and phone markets increasing Apple's market share massively. If they continue buying out companies you are left with a super company that can charge whatever they want because they control almost all of the market.