The aqeedah of the Ahl al-Sunnah is that all believers will eventually enter paradise, as long as they were believers before death. The sinners among them may be forgiven without repentance, or they may be punished for a finite period of time in hell and will then be admitted to paradise.
اتفق أهل السنة على أن المؤمن لا يخرج عن الإيمان بارتكاب شيء من الكبائر إذا لم يعتقد إباحتها، وإذا عمل شيئا منها، فمات قبل التوبة، لا يخلد في النار، كما جاء به الحديث، بل هو إلى الله، إن شاء عفا عنه، وإن شاء عاقبه بقدر ذنوبه، ثم أدخله الجنة برحمته
The Ahl al-Sunnah are in agreement that a believer is not taken out from faith by committing anything from the major sins as long as he does not disbelieve by consider the sin to be lawful. And that if he does any of them (major sins) and dies without repentance, then he shall not be in hell forever, rather he is subject to the will of Allah, if Allah wills he may be forgiven, and if Allah wills he will be punished to the extent of his sin and then admitted into paradise because of Allah's mercy.
— Sharh al-Sunnah
إجماع أهل الحق على أن الزاني والسارق والقاتل وغيرهم من أصحاب الكبائر غير الشرك لا يكفرون بذلك بل هم مؤمنون ناقصو الإيمان إن تابوا سقطت عقوبتهم وإن ماتوا مصرين على الكبائر كانوا في المشيئة فان شاء الله تعالى عفا عنهم وأدخلهم الجنة أولا وإن شاء عذبهم ثم أدخلهم الجنة
The people of the truth are unanimous that
adulterers, thieves, murderers, and those who commit grave sins,
other than associating partners with God, are not considered
unbelievers as a result of their sins. They are believers but their faith
is deficient. If they repent and desist, their punishment is waived, but
if they die persisting in their grave sins, they are left to God to
determine their fate: He may wish to admit them to Heaven directly
or He may punish them first then admit them into Heaven
— Sharah Nawawi
And the support for this are the verses and ahadith on the possibility of forgiveness for everything other than shirk\kufr and on intercession and on taking out of the believers from hellfire. This is already covered extensively on this site and elsewhere.
إن الله لا يغفر أن يشرك به ويغفر ما دون ذلك لمن يشاء
Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills.
— Quran 4:48
ذلك جبريل ـ عليه السلام ـ عرض لي في جانب الحرة، قال بشر أمتك أنه من مات لا يشرك بالله شيئا دخل الجنة، قلت يا جبريل وإن سرق وإن زنى قال نعم
Gabriel said: Give the good news to your followers that whoever dies without having associated anything with Allah, will enter Paradise.' I said, 'O Gabriel! Even if he had committed theft or committed illegal sexual intercourse?' He said, 'Yes.'
يقول الله من كان في قلبه مثقال حبة من خردل من إيمان فأخرجوه
Allah will say. 'Take out (of the Fire) whoever has got faith equal to a mustard seed in his heart.'
As for 42:45, or any other verse which mentions eternal punishment - it is understood to refer to the disbelievers. 'Wrongdoers' is often used as a synonym for 'disbelievers', and the context supports this as it is talking about those who are astray and those who are contrasted with the believers. Similarly there are many other verses where wrongdoers is used as a synonym for disbelievers, such as:
وننزل من القرآن ما هو شفاء ورحمة للمؤمنين ولا يزيد الظالمين إلا خسارا
And We send down of the Qur'an that which is healing and mercy for the believers, but it does not increase the wrongdoers except in loss.
— Quran 17:82
يثبت الله الذين آمنوا بالقول الثابت في الحياة الدنيا وفي الآخرة ويضل الله الظالمين
Allah keeps firm those who believe, with the firm word, in worldly life and in the Hereafter. And Allah sends astray the wrongdoers.
— Quran 14:27
Strictly speaking, disbelievers are a subgroup of wrongdoers (Quran 2:254). However in natural language it is customary to use the name of a general category to refer to a specific part of that group. As an example in English, consider the sentence:
'The Americas won three medals in the Olympics'
Here it is typically understood that 'Americans' means from the country of USA and not all the other countries in the continents of America such as Canada, Brazil, Columbia, Mexico etc. Further it is understood that 'Americans' means some individual athletes from USA and not all the people of USA.
In the same way the Quran often uses words like 'wrongdoers' or 'criminals' to mean only the disbelievers. As this is understood from the context and from the other verses and ahadith.